Springbok front-row pair Adriaan Strauss and Trevor Nyakane, along with Pieter Labuschagne and Jamba Ulengo, have all joined the Bulls.
The Cheetahs quartet are all heading to Pretoria in a major blow for the Bloemfontein-based franchise.
All three forwards will join the Bulls on November 1, while Ulengo has already started training with the Blue Bulls.
Springbok hooker Strauss, who captained the Cheetahs in recent seasons, was South Africa's Super Rugby Player of the Year in 2013 and returns to Loftus Versfeld, where he made his Super Rugby career in 2006 after a seven-year absence. He has signed a two-year deal.
Strauss was a member of the Blue Bulls squad that shared the Currie Cup in 2006 and the Free State side that won it the next year.
He became a Springbok in 2008 and has played 34 times for South Africa (with 5 tries). He is also the Cheetahs' most experienced player with 97 caps, (added to the eight Vodacom Bulls caps).
Springbok prop Nyakane has signed with the Bulls and Blue Bulls till October 2017. Springbok squad member Labuschagne has signed till the end of October 2016 as has Springbok Sevens flyer Ulengo.
The 25-year-old Nyakane, who was first spotted as a youngster playing for the Limpopo Blue Bulls at Craven Week, made his provincial debut for the Free State in 2011, his Super Rugby debut for the Cheetahs in 2012 and his Springbok debut in 2013. He has played four tests and scored one try in his international career this far.
Pretoria-born Labuschagne also came through the ranks at the Free State, having represented the union at school boy, junior and senior level, as well as playing Vodacom Super Rugby for the central franchise.
The 25-year old was part of the Springbok training group in 2013, but injuries in 2014 prevented him from pushing for higher honours.
Ulengo was a regular on the IRB Sevens World Series circuit, having played for the Springbok Sevens team since 2012. He is also a former Toyota Free State age group and Absa Currie Cup player.
BBC's High Performance manager, Xander Janse van Rensburg also confirmed the extension of their current contracts of the Kriel twins, Dan and Jesse, till 2016.
"We are pretty excited about these signings as all of them are proven performers at the highest level," said van Rensburg.
"These players are all very keen to share in our vision of becoming the number one team in both Super Rugby and Currie Cup and to help us achieving those milestones.
"These are important and significant signings, as they show that we are still seen as a pathway to international honours and the winning of tournaments and cups by established, as well as emerging players," Janse van Rensburg said.
"The decision of Adriaan to join us will not also add depth to our hooking position, but with his extensive role as captain, will also provide fantastic leadership and solid international experience."