Ballance was released by Yorkshire this week at his own request, effectively paving the way for him to formally commit to signing a new deal with Zimbabwe Cricket.
The 33-year-old previously represented them at under-19 level but, after moving to England to complete his schooling, went on to play 23 Tests and 16 ODIs for his adopted nation.
He has not been seen in England colours since 2017, comfortably clearing the three-year buffer required to represent a different country, and saw his time in county cricket draw to a regrettable end.
He was named by Azeem Rafiq as one of the Yorkshire team-mates who used racially discriminatory language, claims Ballance admitted and apologised for during a meeting between the former friends earlier this year.
Struggles with his mental health also affected his availability and he did not make a single first-team appearance for the White Rose last season.
Zimbabwe head coach Dave Houghton, who has known Ballance since childhood due to a family connection, had previously suggested he would welcome the batter back into the fold and could offer him several years at the top level.
"I'm thrilled to be joining Zimbabwe Cricket and can't wait to start work with some great coaches and talented players," Ballance said.
"The opportunity to represent Zimbabwe has given me a new-found passion and excitement for the game.
"I have kept in touch with a number of people within Zimbabwe cricket over the years and it has been great to watch their recent progress especially."
Zimbabwe's director of cricket Hamilton Masakadza added: "We are elated to have Gary, an immensely talented and experienced cricketer, back home where it all started for him.
"He is a great addition to our domestic and international set-up and we are looking forward to him making a massive difference for us."
Zimbabwe are hosting next year's qualifying tournament for the 2023 World Cup in India, opening up the possibility of Ballance facing off against England on the global stage.