De Villiers had played six matches for Brisbane Heat in the previous edition of BBL.
That, as well as "uncertainty around travel and conditions" amid COVID-19 pandemic, majorly influenced the great South African's decision.
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In a statement issued by Brisbane Heat, De Villiers, who turned up for the club last season and played six matches with 146 runs at an average of 24.33, mentioned: "with a young, growing family, and the uncertainty around travel and conditions due to COVID19, we reluctantly decided it wasn't going to be this season."
However, the 36-year-old is pretty keen to return to the Brisbane set-up whenever possible.
"I am very open to returning to the club in the future. The team didn't get the results we were hoping for and I consider there is some unfinished business to deal with," he said.
Coach Darren Lehmann said they were really excited with the prospect of having an in-form De Villiers back.
"While things initially looked fine for him to come back, there have been a few factors emerge which have changed everyone's plans," Lehmann said. "The main one, aside from the challenges represented by Covid-19 and international travel, is that AB and his wife Danielle are expecting their third child very soon."
"Naturally we're very pleased for them and know that the next few months will be a very special time for all. We'll stay in contact and see what develops."
"He has been in excellent touch in the IPL for Royal Challengers Bangalore, so he obviously remains a player we'd like to keep working with when the circumstances allow."
While feeling De Villiers' absence, Brisbane Heat will be pleased with the return of unorthodox finger-spinner Mujeeb Ur Rahman to their squad for the season. The team will also have the services of England's talented young batsman, Tom Banton, once again.
BBL teams are now allowed to field three overseas players in their playing XIs.
The dates and venues for the competition are expected to be announced in the coming days.
(Inputs from ESPNcricinfo)