Lilja attended Carl Sandburg High School in Orland Park, Illinois, where he was both a football and baseball standout. As a senior, he received All-Chicago honors as a center and defensive tackle. He accepted a football scholarship from the University of Michigan. Lilja wore #59 for four years as a varsity player from 1977-1980. In 1976, he redshirted as a junior varsity player. As a junior in 1979, he was named the starter at Center, for a team that played in the Gator Bowl. As a senior in 1980, Lilja received numerous awards and honors, including being named the team's co-captain, receiving the University's Myer Morton Award, and being named third-team All-American by the Associated Press. He was named second-team All-American and All-Big Ten by different sports news organizations. He started 24 straight games at center during his junior and senior seasons and is one of eleven centers to become an All-American for Michigan football. During the 1980 Purdue game, Lilja's jersey was ripped to the point where he could not go back out and play. When the equipment staff could not locate his backup jersey, they took the jersey of freshman center Doug James, put it on Lilja, and sent him back into the game. After the game, James got calls from friends expressing surprise that the freshman had gotten playing time in a big game. As the 1980 Big Ten Conference Champions, the team played in the 1981 Rose Bowl, which marked the first bowl game victory for head coachBo Schembechler. It was also Lilja's last game for Michigan, which the Wolverines won 23-6, over Washington. Teammate Brad Bates later recalled: "I was walking off the field with George Lilja, and he said, 'Let's turn around for a Kodak moment,'... 'You could see that big orange backdrop against the mountains. This was Bo's first bowl victory.".
Lilja was selected by the Los Angeles Rams in the fourth round of the 1981 NFL Draft. As a rookie, he suffered an ankle injury and spent the entire year on the injured reserve list. In 1982, he played in all nine games of the shortened strike season, mostly on special teams. He was waived in August 1983.
On September 27, 1983, he was signed by the New York Jets. He played as a backup offensive tackle, before being released on November 15, 1984.
Cleveland Browns
On November 21, 1984, he was signed as a free agent by the Cleveland Browns, to play under interim head coach Marty Schottenheimer. He started in the last game against the Houston Oilers. In 1985, he was named the starter at left guard over Robert Jackson. He contributed to both Earnest Byner and Kevin Mackrushing for over 1,000 yards, becoming just the third running back tandem on the same team to achieve that feat in one regular season. In 1986, he was a backup playing mostly on special teams, on a team with a 12-4 record, that advanced to the American Football Conference championship game against the Denver Broncos in the 1986 NFL Playoffs. Their playoff run included back-to-back overtime home playoff games decided by 23-20 scores. The latter game is known for The Drive. He was released on September 7, 1987.
Dallas Cowboys
On October 14, 1987, he was signed as a free agent by the Dallas Cowboys to provide depth at center. In November, he began sharing snaps with starter Tom Rafferty, with Lilja playing on running downs and Rafferty replacing him in passing situations. In 1988, he was competing with Rafferty for the starting position, until suffering a broken left middle finger. He was released on September 27.
In July 1989, he was signed by the Atlanta Falcons. He was released on September 4. In his career he appeared in 54 games with 17 starts.
Personal life
, Lilja worked at Warren General Hospital and served as a volunteer high school football coach at Warren Area High School, in Warren, Pennsylvania. He is married to his wife Meg, and they have four children, Danielle, David, Bethany, and George III. Lilja is not related to Ryan Lilja. Lilja's parents raised him in a Christian manner with his five brothers and two sisters. Lilja has long been part of Christian athlete groups and writes and speaks about his Christian faith. He espouses the biblical quote:
