Sullivan, a state legislator since 1994, defeated Democrat Doug Dodd, a former Tulsa school board member, in the final count Tuesday night from the 1st Congressional District. With all 292 precincts reporting, Sullivan had nearly 54 percent of the vote to Dodd's 44 percent.
Independents Neil Mavis received nearly 2 percent of the vote and David Fares less than 1 percent.
Sullivan described the victory as "one of the greatest experiences of my life." He was unsure when he would leave for Washington.
Largent, who was an NFL star before he entered politics, plans to resign from Congress on Feb. 15 to run for governor. Gov. Frank Keating is serving his final term.
Keating's wife, Cathy, had been a candidate for the Republican nomination in the 1st District race but she withdrew after Sullivan outpolled her in the Dec. 11 primary, forcing a runoff. She said she wanted to avoid a bitter fight among Republicans.