The 26-year-old was heavily linked with a move to Bucs prior to the current Transfer Window after falling out of favour at the Clever Boys.
Wits central midfielders Ben Motshwari, Granwald Scott and Thabang Monare have been preferred ahead of the Soweto-born player.
Pirates were said to be open to including Abbubaker Mobara in a swap deal which would see the Soweto giants sign Mlambo.
On Monday, Bucs announced that they had reached an agreement with the defending PSL champions for Mlambo.
The deal is subject to a medical according to the Pirates official website.
The Houghton-based outfit released the following statement ahead of their league match with Ajax Cape Town on Wednesday.
"‘Ten Ten’, as the 26-year old is known, will be a valuable addition to the Buccaneers midfield.
"The Mighty Buccaneers are expected to make further announcements as the club looks to bolster the squad as the Absa Premiership season enters its final stretch." a statement read.
It remains to be whether Pirates vice-captain Mobara will join Clever Boys during the current Transfer Window.
The defender-come-mdifielder missed Bucs' 2-0 league victory over Platinum Stars at the Royal Bafokeng Stadium on Saturday.
Wits duo Thulani Hlatshwayo and Ben Motshwari are reportedly on the radar of the Buccaneers.
Mlambo will be hoping to pass his medical and seal his move to the Soweto giants.