Amakhosi are set to announce the arrival of both their new signings, with Frosler joining goalkeeper Daniel Akpeyi from Chippa United at Naturena.
Frosler had initially signed a pre-contract with the Soweto giants, who have pulled out all the stops to land the 21-year-old right-back early.
After turning down a new deal at Wits at the start of the season, the former Amajita star was said to have been banished from the first team. He has failed to make an appearance under coach Gavin Hunt this campaign.
This despite being an integral part of the squad that delivered the club's maiden Absa Premiership trophy just two seasons ago.
The Port Elizabeth-born player, who came through the development ranks at Wits, will offer competition to Bafana Bafana right-back Ramahlwe Mphahlele as well as Kgotso Moleko.
He is also gunning for a return to Stuart Baxter's side ahead of the upcoming Africa Cup of Nations to be hosted in Egypt in June.
Frosler is understood to have added the remaining five months of the current season to his initial four-year deal signed earlier this month.