The Malawi international has established himself as one of the top attackers in the country and his exploits for the Clever Boys have attracted interest from the Buccaneers.
Mhango, who impressed at the recent 2019 Cosafa Cup in Durban, helped Wits clinch the PSL title, MTN8 Cup and Telkom Knockout Cup.
On Wednesday, Bucs announced that they have agreed terms with Students over the services of Mhango ahead of the new 2019/20 campaign.
"Orlando Pirates Football Club can confirm that it has reached an agreement with Bidvest Wits for the services of forward Gabadinho Mhango."
"The 26 year old Malawian international will undergo a medical tomorrow and join his new teammates for the afternoon training session."
"Orlando Pirates Football Club would like to thank Wits’ management for the professional manner that these negotiations were conducted," a club statement read.
Pirates have beaten their PSL rivals Kaizer Chiefs and SuperSport United to the signing of the experienced attacker.
Mhango has been linked with Amakhosi and Matsatsantsa since last year, but he is now set to join the 1995 Caf Champions League winners.
The Chiweta-born player fell out of favour under Wits head coach Gavin Hunt during the recent campaign, and made 12 appearances in the league and scored three goals in the process.
He will compete with the likes of Justin Shonga, Augustine Mulenga and Thembinkosi Lorch in the Bucs attacking department next season.