Roberts was born in 1928 in North Carolina and moved to Waycross, Georgia as an infant, the only child of Pernell Elven Roberts, Sr. (1907–1980), a Dr Pepper salesman, and Minnie (Betty) Myrtle Morgan Roberts (1910–1988). During his high school years, Pernell played the horn, acted in school and church plays and sang in local USO shows. He attended, but did not graduate from, Georgia Tech. Enlisting in 1946, he served for two years in the United States Marine Corps. He played the tuba and horn in the Marine Corps Band, and he was also skilled at playing the sousaphone and percussion. He later attended, also without graduating, the University of Maryland, where he had his first exposure to acting in classical theatre. He appeared in four productions while a student, including Othello and Antigone, but left school to act in summer stock.  In 1949, he made his professional stage debut with Moss Hart and Kitty Carlisle in The Man Who Came to Dinner at the Olney Theatre in Olney, Maryland. Later, he spent eight weeks at the Bryn Mawr College Theatre in Philadelphia, portraying Dan in Emlyn Williams’ Night Must Fall and Alfred Doolittle in Bernard Shaw’s Pygmalion.

Roberts moved to Washington, D.C. in 1950 and supported himself with a variety of jobs while performing with the Arena Stage Theater for two years. He performed in numerous productions, including Steinbeck’s Burning Bright, The Adding Machine, The Firebrand, The Deletable Judge, The Taming of the Shrew (“Petruchio”), Playboy of the Western World, Children of Darkness, School for Wives, The Inspector General, The Glass Menagerie, Mr. Arcularis, Twelfth Night, The Scarecrow, The Importance of Being Earnest, Julius Caesar, She Stoops to Conquer, School for Scandal, Three Men on a Horse, Faith of Our Fathers (Sesquicentennial Amphitheatre) and Dark of the Moon.  He performed with the Port Players, in Milwaukee, in the comedy “To Dorothy a Son,” and other productions. “Roberts again is master of all situations, as he has been in the 9 previous productions of the season”.  He performed with the Brattle Theatre’s production of Othello and Henry IV, Part I, which was later brought to the New York City Center (Playbill, January 1957) and later, Guys and Dolls with the Cohassett Music Circus.

In 1952 he moved to New York City, where he appeared first off-Broadway in one-act operas and ballets with the North American Lyric Theatre, with the Shakespearewrights, at the Equity Library Theatre, and later on Broadway with performances in Tonight in Samarkand (also in Washington, D.C.) The Lovers opposite Joanne Woodward, and A Clearing in the Woods with Robert Culp and Kim Stanley. He won a Drama Desk Award in 1955 for his performance in an off-Broadway rendition of Macbeth, which was followed by the role of Mercutio in Romeo and Juliet. He performed in Twelfth Night, Merchant of Venice, Dr. Faustus, The Taming of the Shrew at the American Shakespeare Festival, and later on Broadway. He performed in St. Joan (1954, Cleveland), Down in the Valley (at the Provincetown Playhouse), The Duchess of Malfi, Measure for Measure, and King John. .

In 1956, he returned to the Olney Theatre, starring opposite Jan Farrand in Much Ado About Nothing with the “Players, Inc. Group”.  The same year, Roberts made his television debut in the “Shadow of Suspicion” episode of Kraft Television Theater, followed by guest- starring roles in Whirlybirds, Gunsmoke, Cimarron City, Buckskin, Sugarfoot and Cheyenne.  He signed a contract with Columbia Pictures in 1957 and made his film debut a year later as one of Burl Ives’ contentious sons in Desire Under the Elms (1958). The film was nominated for a Best Cinematography Academy Award. He also landed character roles in such features as The Sheepman.

He continued to guest star on television shows such as episodes of Shirley Temple Storybook Theater (The Emperor’s New Clothes, Rumplestiltskin, The Sleeping Beauty, and Hiawatha), the live-broadcast Matinee Theater, where he starred in Shakespeare’s Much Ado About Nothing, and in The Heart’s Desire. This was followed by appearances in Trackdown, Buckskin, and episodes of Zane Grey Theater. Roberts guest-starred as Captain Jacques Chavez on the NBC adventure series Northwest Passage (1958), based on the life of Major Robert Rogers in the French and Indian War. He appeared with fellow guest star Fay Spain in the 1958 episode “Pick up the Gun” of Tombstone Territory and played the lead villain in the 31st episode (“Hey Boy’s Revenge”) of Have Gun – Will Travel, portraying a killer boss exploiter of Chinese Coolie laborers. In 1959 Roberts guest starred in episodes of General Electric Theater, Cimarron City, Sugarfoot, Lawman, One Step Beyond, Bronco, 77 Sunset Strip, The Detectives and House Call. Also in 1959, he co-starred with James Coburn in the film Ride Lonesome. “If Roberts felt typecast by Westerns, they also provided his finest role in this film, arguably the greatest of the B-films, starring Randolph Scott and directed by Budd Boetticher. Roberts recognised the film’s classic structure; his engaging outlaw, Sam Boone, counterpoints Scott’s granite-faced Ben Brigade, maintaining the tension of whether they will work together or clash. He similarly played off James Coburn, who was making his film debut as Boone’s quiet sidekick, Whit.”  The same year he was cast in Bonanza.

After Bonanza, Roberts played the straw hat circuit, regional theaters, and episodic TV, which gave him the opportunity to play a wide variety of roles. He toured with musicals such as The King and I, “Kiss me Kate,” Camelot and The Music Man and dramas such as Tiny Alice. He played Jigger in an ABC television presentation of Carousel and was featured in a CBS Playhouse production, Dear Friends.  In 1967, Roberts starred in the lavish, but short – lived David Merrick production of Mata Hari, directed by Vincente Minnelli. The show had a much publicized “chaotic” preview performance due to technical problems stemming from lack of rehearsal time at the Kennedy Center, Washington, D.C., where the preview performance took place. “What was offered the people of Washington was a dress rehearsal. David Merrick spoke to the audience beforehand warning them of this”. Problems were corrected by the official opening night, when the show received good reviews for Roberts, musical score and lyrics, stage design and costumes, but poor reviews for its co-star and other aspects of the production. The show, nevertheless was thought to have the potential to continue to Broadway. “Mata Hari was a show with a great story, two fascinating characters and some accessory mess that could have easily been tidied up by anyone but Vincente Minnelli.” But Merrick, “instead of bringing someone to clean house closed the production down” (“Opening A New Window: The Broadway Musical in the 1960s,” p. 205 Ethan Morrden, October 29, 2002).

In 1972, Roberts returned to Broadway and toured with Ingrid Bergman in Captain Brassbound’s Conversion, in which he played the title role.[26] “Particularly helpful is Pernell Roberts in the acted upon title role… This actor is a sturdy, not unamusing leading- man type and may his appearance as a Bergman costar be rewarded beyond Bonanza.”  In 1973, Roberts was nominated for a Joseph Jefferson Award for his performance in Welcome Home, at the Ivanhoe Theatre in Chicago.  The same year, Roberts starred as Rhett Butler opposite Lesley Ann Warren, in another major production, Gone with the Wind, at the Chandler Pavilion in Los Angeles, again receiving good personal reviews, amidst weak reviews for the rest of the show.  Additional stage credits after Bonanza include Two for the Seesaw, A Thousand Clowns, One Flew Over the Cuckoo’s Nest, Any Wednesday and The Sound of Music (as Captain von Trapp).  He did The Night of the Iguana while still playing in Bonanza in 1963.

Roberts guest starred in TV shows such as The Girl from U.N.C.L.E., The Virginian, The Big Valley, Lancer, Mission: Impossible, Marcus Welby, M.D., The Wild Wild West, Ironside, The Rockford Files, Gunsmoke, Mannix, Vega$, The Odd Couple, Hawaii Five-O, The Love Boat, The Hardy Boys/Nancy Drew Mysteries, San Francisco International Airport, Nakia, Night Gallery, The Bold Ones, The Quest, Police Story, Most Wanted, Westside Medical, Man From Atlantis, Jigsaw John, Sixth Sense, Quincy, M.E., The Feather and Father Gang, Hawkins, Men from Shiloh, Perry Mason, Wide World of Mystery, and The Six Million Dollar Man, and appeared in mini-series, including Captains and the Kings, Centennial, Hotel, The Immigrants, and Around the World in 80 Days. He starred in two cult films, Four Rode Out and Kashmiri Run, directed by the veteran TV director John Peyser, and made some feature films, including The Magic of Lassie. He co-starred or was featured in several TV movies, including, The Adventures of Nick Carter, Dead Man on the Run, The Night Rider, The Silent Gun, The Lives of Jenny Dolan, The Deadly Tower, Hot Rod, Desperado, The Bravos, High Noon, Part II, and Assignment Munich.

In 1979, Roberts again achieved “superstar” status (TV Guide, 1982) as the lead in Trapper John, M.D. (1979–1986), receiving an Emmy nomination in 1981; and playing the character twice as long as Wayne Rogers had (1972–1975) on CBS ’​s M*A*S*H series. Roberts told TV Guide (1979) that he chose to return to weekly television after watching his father age, and realizing that it was a vulnerable time to be without financial security. “The show allowed Roberts to both use his dramatic range and address issues,” wrote The Independent.  Of the period between series, Roberts said he enjoyed moving around and playing different characters. During that time, he also toured university campuses conducting seminars on play production, acting and poetry.  In 1988, Roberts co-starred with Milla Jovovich in the TV movie The Night Train to Kathmandu.  He guest starred as Hezekiah Horn in the powerful Young Riders episode, “Requiem for a Hero,” for which he won a Western Heritage Award in 1991.  In interviews, Roberts had described television as a “director’s and film cutter’s medium”, but he himself was described as a “born television actor……..low key”. (TV Guide, 1982).  In the 1980s and 1990s, playing off his Trapper John M.D. persona, Roberts acted as TV spokesman for Ecotrin, a brand of analgesic tablets.  Recent roles included Donor (thriller, 1990) with Melissa Gilbert and Checkered Flag (action, 1990).  He appeared as captain of the CBS teams for Battle of the Network Stars 11 and 12.

He narrated documentaries, including the National Geographic episode, “Alaska, The Great Land,” in 1965; “In the Realm of the Alligator,” in 1986; the TV special Code One, about the work of paramedics, 1989 and, “The Mountain Men” episode of the History Channel, 1999.  From 1991 to 1993, in his last venture into series television, Roberts lent his distinctive voice to host and narrate the TV anthology series, FBI: The Untold Stories.  He made his last TV appearance in 2001 on an episode of Diagnosis: Murder, updating a Mannix character he had portrayed decades before.  In his later life, and after the death of all of his former Bonanza co-stars, Roberts “jokingly referred to himself as, ‘Pernell, the last one, Roberts’, (New York Times, January 26, 2010; Cowboydirectory.com). He read Bonanza Gold Magazine, which was like looking at an old family album he said, and watched reruns of Bonanza when he wanted to see old friends (Bonanza Gold Magazine, 2005).

Roberts married four times, first in 1951 to Vera Mowry — a professor of theater history at Washington State University and subsequently Hunter College as well as professor emerita of the Ph.D. Program in Theatre at City University of New York — with whom he had his only child (Jonathan Christopher “Chris” Roberts, b. October 1951). Pernell and his first wife later divorced. Chris Roberts, who lived variously in California and New York, attended Franconia College and died in a motorcycle accident in 1989 at age 38, sometimes reported as age 37.  Roberts married Judith Anna LeBrecque on October 15, 1962; they divorced in 1971. He subsequently married Kara Knack in 1972, divorcing in 1996.  At the time of his death — from pancreatic cancer on January 24, 2010 — Roberts was married to Dr. Eleanor Criswell.  Shortly after his death, his friend and former costar, Gregory Harrison, released a statement: “Pernell was a wonderful man, a good friend, and a big part of my life, especially when I was just beginning as an actor. He was a true inspiration to me, as he was to many actors over the years. I was so lucky to have shared the screen with him for nearly eight seasons, and am deeply saddened at his passing. Fortunately, he lives on in the memories of his fans, and in the hearts of the lucky people, like you and me, that he touched personally. I’ll be forever grateful to him.”