The idea took root when Shaun Livingston went fourth overall to the Clippers in the 2004 NBA draft.

Then a slender 18-year-old with a throwback playing style that befit his bushy afro, Livingston decided one way he wanted to use his newfound wealth: Concordia Lutheran, the Peoria, Ill., grade school where he had learned the game, required a sizable donation to start expansion and renovation.

His desire to give back persisted as Livingston suffered a career-threatening leg injury in 2007 and pingponged between more than a half-dozen teams. On Sunday, a Warriors off day, he spoke at the dedication ceremony for Concordia Lutheran’s 16,000-square-foot expansion.

“It was a no-brainer for me,” Livingston said of his $1 million gift to the school. “It’s not necessarily about the money, even though it’s a lot of money. It’s about fulfilling my responsibility.”

Throughout his nomadic NBA career, Livingston has made a point to visit Peoria multiple times a year. He holds an annual basketball camp there in the summer. In July 2015, after his Golden State team won the NBA title, he brought the Larry O’Brien Trophy to his alma mater, Peoria Central High School.

Long overshadowed in the basketball community by Chicago, Peoria (population: 115,828) is better known for being the home of late comedian Richard Pryor than of elite athletes. Livingston, 31, reckons that his own story falls in line with his hometown’s workmanlike ethos.

Once a potential franchise player for the Clippers, his professional life derailed when he came down awkwardly after a missed layup nine years ago and snapped his left leg in half. Livingston missed the 2007-08 season as he relearned to walk.

To resuscitate his career, he slogged through a stint with Oklahoma City’s Development League affiliate and signed two 10-day contracts with the Wizards. In July 2014, when he signed a three-year deal with the Warriors, Livingston already had been on eight NBA teams in eight years.

Such instability made it difficult for him to commit to any significant donations. Though Livingston was reminded of the promise he had made to himself whenever he saw Concordia Lutheran’s tiny, outdated gym, he needed to plan for life after basketball.

“I was trying to do it the right way,” Livingston said.

On July 4, the day Kevin Durant announced his intention to sign with the Warriors, team officials informed Livingston they were retaining him for $5.7 million this season. It was enough to guarantee the long-term financial security he desired. After meeting with his money manager, Livingston contacted the school he had led to state basketball titles in the seventh and eighth grades.

His seven-figure donation covered the rest of the $3.2 million in funding needed for the school’s new gym, stage with a sound system for band and orchestra players, and EF-5-rated storm shelter. It was a project that Concordia Lutheran officials had started planning in 1994, when Livingston was a third-grade student at the school.

Late Saturday night, while his teammates flew from Milwaukee to Indianapolis, Livingston made the four-hour drive to Peoria with his father, Reggie. During the dedication ceremony Sunday at Concordia Lutheran, Livingston introduced his grade-school coach, Tom Ruppert.

As the school’s longtime athletic director, Ruppert had handled everything from coaching to scheduling to cleaning. Nearly a decade ago, when Livingston transitioned from franchise cornerstone to role player, he often thought about how Ruppert had not deemed any task too small.

“He was just all about giving God the glory,” Livingston said. “He never wanted the credit.”

Concordia Lutheran’s gym and other facilities will be named the Ruppert Center. On the basketball court, scribbled in big black paint, is Livingston’s signature.

Connor Letourneau is a San Francisco Chronicle staff writer. Email: cletourneau@sfchronicle.com

Friday’s game

Who: Warriors (13-2) at Lakers (8-8)

Where: Los Angeles

When: 7:30 p.m.

TV/Radio: CSNBA/95.7