Sane featured in all five games for Germany at EURO 2024 before undergoing surgery in July, and returns as Bayern also begin their Champions League campaign at home to Dinamo Zagreb on Tuesday.
"We have a lot of players and we need all of them. Aside from the long-term injured, all the players are fit," Kompany told reporters.
"We've got a week with three matches coming up and we're looking forward to it. Leroy will also be in the squad."
Sane also struggled with injuries towards the end of last season, making one appearance in Bayern's final seven league games, having scored eight goals in their opening nine matches.
"He had a really good first half of last season and was involved in a lot of goals," Bayern's sporting director Christoph Freund said.
"In the early part of this year, he had constant battles with injuries and pain, but he battled on and played through it.
"The nice thing now is that he's pain-free. We're glad he's back and properly fit."
On Saturday, Bayern face promoted side Kiel, who are in the Bundesliga for the first time, and Kompany knows what it is like to take a side up from the second tier after his time in England with Burnley.
"I experienced it myself last year. We completely dominated in the second division with Burnley, and then we got promoted to a different league and struggled," Kompany said.
"But you do all the work for exactly these games and I imagine that Kiel are looking forward to it.
"They're flexible and good on the ball. They were dominant last season and even though they've been promoted that's stayed in the team."
Bayern are second in the standings, level on six points with leaders Heidenheim and third-placed RB Leipzig, while Kiel are 16th without a point after their opening two games.