Lehmann returns to the Heat for a second stint as head coach, having previously led them to the 2012/13 title in the second edition of the domestic Twenty20 tournament.
"It was a wonderful experience at the time to be involved with building the Brisbane Heat at the start of the BBL, and we had plenty of fun along the way," the 49-year-old former test batsman said.
"I am looking forward to getting to work and helping the Heat play some outstanding cricket, have some fun, and provide our fans with a great experience."
Lehmann, who replaces the outgoing Daniel Vettori, will start the role next week.
Nicknamed 'Boof', Lehmann was contracted as head coach of Australia through to this year's Ashes series but resigned in tears last March after Steve Smith, David Warner and Cameron Bancroft were banned for the 'sandpaper-gate' scandal.
He was cleared of wrongdoing by governing body Cricket Australia but carried much of the blame in the eyes of local media for failing to rein in player misconduct.
"It was a tough time for everyone involved, none more so than the three players," Lehmann, who guided Australia to two Ashes victories and the 2015 World Cup win on home soil, told reporters on Thursday.
"So for me it's a case of really enjoying the game again. I went away and watched the game all summer, which was absolutely fantastic."
He added that he had no ambitions of coaching at the national level again.
"No, I'm not travelling 300 days away again a year and I don't think my wife would let me either," he said.
The Heat finished fifth in the 2018/19 tournament won by Melbourne Renegades.
(Reporting by Ian Ransom; Editing by Nick Mulvenney)
