Despite his considerable character issues, with his strong performance, Lawrence Phillips was drafted sixth overall in the 1996 NFL Draft by the St. Louis Rams. Several teams with higher picks let it be known that they passed on him due to his off-the-field troubles. He was widely expected to be selected by the new Baltimore Ravens with the fourth pick to fill their vacant running back position. However, they decided to select the best available player regardless of position and selected future eleven time pro-bowler and future Pro Football Hall-of-Fame offensive tackle Jonathan Ogden. During the draft, ESPN analyst Joe Theismann stated in regard to Phillips: “Everybody’s called him the best player in the draft.” The Rams thought so highly of Phillips that on the same day of the draft, they traded his predecessor, future Hall of Famer Jerome Bettis, to the Pittsburgh Steelers. On July 29, 1996, Phillips signed a three-year, $5.625-million contract. He received no signing bonus, but his salaries were $1.5 million in 1996, $1.875 million in 1997 and $2.25 million in 1998. Also, he had a chance to receive some guaranteed money in the future if he met certain conditions. The chaos he created at Nebraska continued in St. Louis; in less than two years with the Rams, he spent 23 days in jail. In 1996 Lawrence Phillips had played 15 games with 11 starts. He carried the ball 193 times for 632 yards for 4 touchdowns. In 1997, Phillips surpassed his entire 1996 total in only 10 games and nine starts, rushing for 634 yards. However, on November 20, the Rams abruptly released him. According to Rams team officials, coach Dick Vermeil had told Phillips that he was being demoted to second string due to his inconsistent performance and inability to stay out of trouble. Phillips stormed out of the Rams’ facility and missed that day’s meeting and practice. The Rams lost patience with him and decided to cut ties with him. A teary-eyed Vermeil at the time called Phillips potentially the best running back he had ever coached.

Lawrence Phillips returned stateside with the San Francisco 49ers in the Fall of 1999. The 49ers interviewed him several times before seemingly being assured that he had put his past difficulties behind him, though general manager Bill Walsh told him that the 49ers would not hesitate to cut him if he stepped out of line. He was in contention for the starting job before pulling a hamstring in training camp. Additionally, his blocking left much to be desired. He was beaten out for the starting slot by Charlie Garner. He did, however, become the 49ers’ primary kick returner. Although Phillips stayed out of trouble off the field, his on-field performance was of greater concern to the 49ers. His blocking skills were so suspect that he was almost never in the game on passing downs. Their concerns were validated during a Monday Night Football game against the Arizona Cardinals, when cornerback Aeneas Williams rushed in on a blitz and Phillips failed to pick it up. Williams ended up knocking Steve Young unconscious on the play with a hard, but clean, hit. Young suffered what would prove to be a career-ending concussion; he did not play again for the rest of the season and was all but forced to retire. In the same game, Phillips ran for a 68-yard touchdown to put the game away 24–10, outrunning Williams to the end zone. Nonetheless, his missed block on Williams led the 49ers to question his work ethic.

By November, the 49ers had lost patience with Lawrence Phillips. According to coach Steve Mariucci, Phillips had actually begun losing interest early in the season, to the point that he was finding “reasons and ways why he shouldn’t practice.” However, the situation came to a head in the run-up to the 49ers’ game against the New Orleans Saints. Phillips refused to practice at all on November 10 and 12, and openly mocked coaching directives. Mariucci called a meeting with his staff, at which Phillips’ position coach, Tom Rathman (coincidentally, a fellow Cornhusker), told Mariucci that he was at his wit’s end with Phillips. Rathman even threatened to stay in San Francisco if Phillips made the trip. That night, the 49ers handed Phillips a three-game suspension for conduct detrimental to the team. Walsh said soon after Phillips was suspended that he could not envision Phillips playing another down for the 49ers. On November 16, Mariucci announced that the 49ers would cut ties with Phillips at the first opportunity. In making the announcement, Mariucci said that the only reason the 49ers did not release Phillips right away was that his entire signing bonus would have counted against the team’s salary cap for 1999, thus tying up nearly all of their cap room. Finally, on November 23, 1999, the 49ers waived him.

On August 21, 2005, Lawrence Phillips was arrested for assault after allegedly driving a car into three teenagers following a dispute with them during a pick-up football game in Los Angeles, California. At the time of the arrest, Phillips was also wanted by the San Diego Police Department in connection with two alleged domestic-abuse incidents involving a former girlfriend, who claimed that Phillips had choked her to the point of unconsciousness. In addition, the Los Angeles Police Department was seeking Phillips in connection with another allegation of domestic abuse that had occurred in Los Angeles. In March 2006, Phillips was ordered to stand trial on charges of felony assault with a deadly weapon stemming from the August 21, 2005, incident. On October 10, 2006, he was found guilty of seven counts. On October 3, 2008, he was sentenced to 10 years in a California state prison. While serving that sentence, Phillips was convicted in August 2009 for the assault on his former girlfriend Amaliya Weisler on seven counts, including assault with great bodily injury, false imprisonment, making a criminal threat, and auto theft. On December 18, 2009, Phillips was sentenced to 25 years in prison on the 2009 convictions, to run consecutive to the 2008 sentence (which was reduced to just under 7 years), for a term of 32 years.

Lawrence Phillips was admitted to the California Department of Corrections and Rehabilitation on October 16, 2008 and was incarcerated at Kern Valley State Prison. Under California law, since his crimes harmed other persons, Phillips was required to serve at least 85 percent of his sentence before being eligible for time off. On April 12, 2015, Phillips’ cellmate Damion Soward, the cousin of former NFL wide receiver R. Jay Soward, was found dead in the cell the two men shared. Soward, who was serving a sentence of 82-to-life for a murder conviction, was choked to death, and Phillips was regarded as the prime suspect in the case. On September 1, 2015, Lawrence Phillips was charged with first-degree murder in Soward’s death. On November 9, 2015, the prosecutor was granted a motion to reconsider whether to seek the death penalty. Lawrence Phillips was awaiting trial and in segregated custody when he was found unresponsive in his cell by correctional officers around midnight on January 12, 2016, and pronounced dead at 1:30 AM, in what is suspected as a suicide. The day before, a judge had ruled that there was enough evidence to bind Phillips over for trial in the murder of Soward. On January 15, 2016, it was announced that Phillips’ family had agreed to donate his brain to be examined for chronic traumatic encephalopathy (CTE) at Boston University. A coroner determined that Lawrence Phillips hanged himself in prison, and had a “Do Not Resuscitate” note taped to his chest according to the Omaha World-Herald.