Rybakina is through to her first major final since Sabalenka produced a three-set comeback win to lift her first Grand Slam trophy in Melbourne three years ago.
The Kazakh fifth seed will relish the opportunity of a rematch, having won each of her last nine matches against fellow top-10 players, including world number two Iga Swiatek in the quarter-finals and now sixth seed Pegula.
Rybakina appeared set to make serene progress to the final after polishing off the first set with an assured forehand winner and maintaining momentum by striking with a break early in the second.
A rare moment of encouragement for Pegula was short-lived as Rybakina responded to a first loss of serve by breaking back immediately and serving her way to a 5-3 lead.
But there were further twists to come as Pegula escaped three match points on serve before capitalising on a poor game from Rybakina to level at 5-5 and tee up a dramatic conclusion.
Rybakina once again reset impressively to create a second chance to serve out victory, only for a resurgent Pegula to force a tie-break.
In keeping with the preceding games, the topsy-turvy tie-break swung back and forth, but Rybakina held her nerve through two set points and clinched her fourth match point with a backhand winner.
No player on the WTA Tour boasts more wins than Rybakina since the end of Wimbledon last year (37), with the only defeat in her past 20 matches coming against Karolina Muchova in Brisbane earlier this month.
