The two Tshwane clubs on Monday reached an agreement on Brockie's move to Chloorkop, as earlier reported by KickOff.com.
In a statement released by Matsatsantsa, CEO Stanley Matthews said: "It’s never easy to lose a key player like Jeremy, especially off the back of three great seasons with us in which we made five cup finals and he became the second highest scorer at the club.
"We also understand that at his age this is Jeremy’s last big move and opportunity to secure his financial future.
"Given that he has made a significant contribution to the club on and off the field, our board have agreed to sanction his move to Mamelodi Sundowns and we wish him well in his future."
The deal, which has been in the works for several months, has been concluded in the nick of time as The Brazilians will look to register the New Zealand international for their 2018 CAF Champions League campaign before the deadline of January 31.