In the championship game, the Titans leaned even more of their leader.
Realmuto carried 42 times for 125 yards.
Carl Albert's defense also came through big, forcing five turnovers, two of which led to Titans' touchdowns.
The first came quickly, as Jeremiah Reed jumped on Kevin Lamb's fumble on the opening drive and nine plays later, Realmuto gave Carl Albert the lead with a 1-yard run.
The Titans then jumped up 14-0 on a hook and lateral play, with Realmuto first finding Walker, who pitched to sophomore Taylor Hawkins who completed the 23-yard touchdown play.
Bixby cut the lead to a touchdown late in the first half but could never find much consistency offensively, as the Titans held Bixby's normally potent offense to just 159 yards.
"We couldn't move the ball offensively," Bixby coach Pat McGrew said. "Defensively, we played as well as we could have. We had a chance to tie it there early in the second half but give credit to them for making some big plays."
Carl Albert is fifth all-time in state titles, breaking a tie with Thomas. Only Ada (19), Clinton (15), Morrison (14) and Jenks (12) have more.
The teams had played in each of the last two postseasons, with Bixby winning two years ago after the Titans built up a big early lead. Carl Albert won 44-6 in the second round last year.
"This is exactly the way I thought it would feel," Walker said. "Defense wins championships and we knew we had to step it up. We couldn't get too excited because we remember what they did to us when we were sophomores. We just kept playing our game."