In 1976 he married his childhood sweetheart. They had a daughter, Brandie in 1980 and a son Glen in 1987, who was named after Lanier’s younger brother who was killed in a motorcycle accident at the age of 16. He has other siblings as well.

Lanier began his motorsport career in 1978, following a meeting with the Sports Car Club of America at an auto show taking place in Miami Beach Convention Center on how to make a start in racing, he bought himself a 1957 Porsche 356 Speedster, where he used it to compete in E Production at the SCCA Southeast Regional Championship, eventually winning the class in 1980.

His growing up in Florida during his youth has been suggested as a potential precursor to his involvement in the drug trade in 1978.

In 1984, after driving for a variety of teams in the previous seasons, including a 2nd at the 24 Hours of Daytona, he formed his own team, Blue Thunder Racing, with Bill Whittington and crew chief Keith Leyton consisting of two March GTPs.

Lanier began to focus on his Indycar career, with the hope of winning the Indianapolis 500. He drove for Arciero Racing, intending to commit full-time for the 1986 season. For the following season, Lanier would also drive for Joest Racing for both Daytona 24 Hours and Miami. After a poor form in the previous year, Lanier would improve his form by finishing six of the nine races he entered including his 10th-place finish at the Indy 500, winning the Rookie of The Year honor and taking the fastest qualifying time for a rookie that year, an average of 209.964 MPH beating the previous record set by Michael Andretti in 1984. His final race was at the Michigan 500 where he collided into a wall at 214 MPH following a tire blow out, breaking his right femur and was shortly arrested. Prior to that, he drove in 18 CART races in 1985 and 1986.

In 1986, Lanier became romantically involved with Maria De La Luz Maggi.

Many of these narcotics were distributed in Illinois, therefore he was indicted by Judge James L. Foreman in the Southern District of Illinois in January 1987. He was convicted of importing and distributing over 300 tons of Colombian marijuana, believed to be worth $68 million by prosecutors and was due to be sentenced when he disappeared.

Randy Lanier and his partner Ben Kramer received life without parole sentences on 4 October 1988 under the newly enacted Continuing Criminal Enterprise statute (also known as the “Super Drug Kingpin” law), owing to their refusal to cooperate with the prosecution. The Whittington brothers who were also involved received a lighter sentence. Lanier filed an appeal based on the fact that later RICO convictions were not nearly as lengthy, but lost the appeal. He was initially placed in Leavenworth Federal Penitentiary and was later transferred to the higher security United States Penitentiary I in Coleman. He spent his time in prison exercising, playing chess and answering letters sent by race fans.

Maggi, who married Lanier on August 31, 1990 at Oxford Federal Correctional Institution in Wisconsin., was sentenced on April 30, 1993 to nine years in prison for money laundering. She pleaded guilty in September the year previously to conspiracy and obstruction and later successfully appealed to have it reduced from 108 months to 97.

In 2015 Lanier took part in a race in Mid Ohio, driving for Rally Baby Racing, which was covered in-depth by Road & Track magazine.