Buttler missed the entire T20I series against Pakistan as he was recovering from a calf injury.
Buttler couldn’t feature in England’s 4-3 T20I series win over Pakistan as he was recovering from a calf injury.
"I'm back to 100 percent," Buttler told reporters on the eve of the T20I series opener against Australia.
"Had a good time in Pakistan rehabbing, probably could have played earlier, but with the World Cup around the corner, it was the right thing to do."
Buttler's return to the playing XI means Alex Hales and Phil Salt would compete with each other for the second opener's slot.
"We have great options at the top of the order with guys in really good form in Pakistan," the England captain said.
"They're both excellent options. Whoever I partner with will have a great go at it."
While Jos Buttler’s comeback will bolster England’s batting line-up, Liam Livingstone's ankle injury is a cause of concern for them heading into the T20 World Cup 2022, slated to get underway on October 16.
"(He) is still a little way off at the minute so he's building back," he said. "Hopefully he'll get back to full fitness before the start of the World Cup."
Buttler also said ace all-rounder Ben Stokes would bat higher in their line-up.
"Ben Stokes is someone we want to try to give as much opportunity to impact the game as possible," Buttler said. "Try to get him up the order as high as we can, give him as much responsibility as possible and allow him to play his way to get the best out of him."
(With Reuters inputs)