Cowlings was born on June 16, 1947, in San Francisco, and was raised in its Potrero Hill neighborhood. There, he was a member of the Superiors social club, which held meetings at the Booker T. Washington Community Center. He attended Galileo High School, where he played football with O. J. Simpson. He and Simpson became friends. After high school, the pair attended City College of San Francisco, where they played on the football team.

Cowlings was a close friend of O. J. Simpson, whom he has known since childhood. They were teammates at Galileo High School, San Francisco City College, USC, the Buffalo Bills, and the San Francisco 49ers. Cowlings dated Simpson’s first wife Marguerite Whitley while they were attending Galileo High School and when they were having issues as a couple, Simpson stepped in as a mediator, but the discussion turned into a relationship and they would eventually marry in 1967; Cowlings was reportedly angry at the time, but their friendship prevailed. They remained close friends and confidants through the years, with Cowlings being the godfather of Simpson’s son Jason and a groomsman at Simpson and Brown’s wedding in February 1985. Cowlings was also the ring bearer at mutual friends Robert and Kris Kardashian’s wedding in July 1978.

Cowlings was drafted fifth in the first round of the 1970 NFL Draft by the Buffalo Bills. He was a starter his first three years in Buffalo, but he was traded to Houston Oilers after the 1972 season. He played all 14 games for the Oilers in both 1973 and 1974, but he played just five games in 1975 for the Rams. In 1976, he became a charter member of the Seattle Seahawks, after being signed off the waiver wire when the Rams released him at the end of the pre-season. He played just one game, due to an injury he suffered while playing for the Rams in an exhibition game against the Seahawks. He returned to the Rams in 1977, Played with CFL Montreal Alouettes 1978, and finished his career in 1979 with the San Francisco 49ers.

Cowlings’ first film role was in the 1985 film Bubba Until It Hurts, starring Bubba Smith. He had a recurring minor role as Coach Nabors in the HBO football sitcom 1st & Ten, which also starred Simpson. Cowlings also served as a technical football advisor on the football scenes in the 1991 Tony Scott film, The Last Boy Scout.

Following the murders of Nicole Brown and her friend Ronald Goldman on June 12, 1994, in which Simpson was a person of interest, Brown’s funeral took place in the St. Martin of Tours Catholic Church in Brentwood on June 16, Cowlings’ 47th birthday; Cowlings served as a gatekeeper and pallbearer at the funeral.

In 1994, Cowlings’ 1993 Ford Bronco from the low-speed chase was purchased by Simpson’s former sports agent Mike Gilbert and two other men, then ended up sitting in a parking garage for the next 17 years (1995-2012), where it was rarely used. As of 2017, the vehicle was on loan to the Alcatraz East Crime Museum where it was put on display as part of an exhibit on the O. J. Simpson murder trial.

Following the acquittal of Simpson in October 1995, the families of Nicole Brown and Ronald Goldman filed a civil suit against Simpson for wrongful death. Cowlings was subpoenaed and during both the deposition and trial took the Fifth Amendment when asked what he was doing between June 13, 1994, when Simpson returned from Chicago, and the freeway chase on June 17, 1994, as he could still be charged for aiding and abetting. However, he testified that he had seen Simpson throw out Brown’s clothes from their apartment during an argument in 1979 and that while he was driving Brown to a hospital on New Year’s Eve 1989, she told him Simpson hit her, which (along with Brown’s recorded 911 calls, pictures of her with bruises, and similar witness testimonies that concern physical aggression on Simpson’s part against Brown) contradicted Simpson’s civil trial testimony that he had never been abusive during their marriage. Simpson was found liable for both deaths in February 1997.

In 2012, Fox News examined the lives of key individuals in the Simpson case and found that Cowlings was reportedly working as a handbag sales representative. In 2014, an ex-teammate told USA Today that Cowlings worked for B. Wayne Hughes, founder of Public Storage. Six months later, USA Today quoted retired tennis player and friend of Cowlings, Joe Kolkowitz, saying that Cowlings had retired and is still living in Southern California.

According to TMZ in 2016, Cowlings had reportedly threatened to sue FX if he was portrayed negatively in the critically acclaimed series The People v. O. J. Simpson: American Crime Story, in which he is portrayed by Malcolm-Jamal Warner.

In March 2018, O.J. Simpson (after his parole for armed robbery and kidnapping) stated that he may have chronic traumatic encephalopathy (CTE), a neurodegenerative disease common in athletes that have suffered numerous head wounds or concussions. Simpson said that close friends and former teammates, including Cowlings, also struggle with the symptoms of CTE.