South Africa trio Steven Kitshoff, Siya Kolisi and Damian de Allende have committed to Stormers until the end of the 2019 Super Rugby season.
Prop Kitshoff opted to end a two-year spell in the Top 14 with Bordeaux Begles to return to Stormers and has signed a two-year contract.
Springboks flanker Kolisi and centre De Allende have extended their stays with the Cape Town franchise for another two years.
Stormers director of rugby Gert Smal said: "We have a strong group of senior players that will take us forward in the next few years and provide crucial guidance for the young talent we have coming through the ranks all the time."
Western Province Rugby Group CEO Paul Zacks added: "These players are already established seniors despite their relatively young age and having them on board for the next two years is a massive boost for us.
"I look forward to seeing all three players take their careers to the next level at Newlands."
Bongi Mbonambi, Frans Malherbe, Eben Etzebeth and Pieter-Steph du Toit have also signed new deals with Stormers until 2019.