The Lakers announced about 30 minutes before tipoff that Davis, who missed the entire second half of Game 4 and all of Game 5 because of a groin injury, will start in the win-or-go-home game.
Lakers head coach Frank Vogel told reporters before the contest that the decision to play Davis would depend on the team's medical staff after they evaluated the eight-time NBA All-Star selection at the arena.
The Suns expected Davis, who averaged 34 points and 10.5 rebounds in the Lakers' two wins in the series, would be available in Game 6.
"We've prepared for Anthony to play," Suns head coach Monty Williams said Thursday.
The seventh-seeded Lakers trail the No. 2 seed Suns 3-2 in the best-of-seven series. If the Lakers fall to Phoenix on Thursday, they would become just the sixth defending champion in league history to lose in the first round of the playoffs the following year.
Conley exited the top-seeded Jazz's series-ending Game 5 victory over the Memphis Grizzlies in the second quarter Wednesday after experiencing right hamstring soreness. He didn't return to that game.
The 33-year-old Conley averaged 17.4 points and 8.6 assists per game in the first-round series against his former team.