Rosenior, who was Rooney's assistant at Derby County and is currently in charge of Ligue 1 side Strasbourg, is the front-runner to replace Enzo Maresca after the Italian left Stamford Bridge last week.
“Liam was so important for me,” the former Manchester United striker said on the BBC’s The Wayne Rooney Show.
“He was incredible in his coaching ability.
"I was more of the manager dealing with players and everything, but I learned a lot from him from that point of view. He’s done a great job as a whole," added Rooney.
Rosenior, 41, previously managed Hull City before joining Strasbourg in July 2024. He led the French club to a seventh-place finish in Ligue 1.
"If he goes in there (Chelsea), he won’t disappoint,” Rooney added.
“He’s been waiting for an opportunity like this.
"If you don’t take it now, then you’re never going to take it. He’s done his apprenticeship, he’s done his work to get to that job.”
Chelsea, who are fifth in the Premier League, will face Fulham on Wednesday.