As it happened: Chiefs v Stormers
James Lowe, Tom Marshall and Tawera Kerr-Barlow scored earlier tries, while All Black flyhalf Aaron Cruden added 11 points for the Chiefs, who have won all three of their games this season and lead the New Zealand conference on 13 points.
Stormers flyhalf Demetri Catrakilis slotted two first half penalties for the visitors before Gio Aplon and Nizaam Carr scored second half tries as the visitors looked to stage a remarkable comeback.
Replacement flyhalf Peter Grant converted both tries for the visitors, who had battled back from 24-6 down to 24-20 with five minutes remaining before Koloamatangi's late effort sealed the win and the bonus point.
Stormers captain Jean de Villiers was in no mood to celebrate playing his 100th Super rugby game.
"We didn't play well, it was obviously not the result we wanted," he said. "We did show heart at some stages of the game but at the end it was pretty disappointing.
"The Chiefs put us under a lot of pressure, there's a reason they've been champions for the last two years."
Scorers:
Chiefs - Tries: James Lowe, Tom Marshall, Tawera Kerr-Barlow, Tevita Koloamatangi, Tanerau Latimer; Conversions: Aaron Cruden (4); Penalties: Cruden
Stormers - Tries: Gio Aplon, Nizaam Carr; Conversions: Peter Grant (2); Penalties: Demetri Catrakilis (2)
Teams:Chiefs
15 Gareth Anscombe, 14 Tim Nanai-Williams, 13 Charlie Ngatai, 12 Tom Marshall, 11 James Lowe, 10 Aaron Cruden (captain), 9 Tawera Kerr-Barlow, 8 Liam Squire, 7 Tanerau Latimer, 6 Liam Messam, 5 Brodie Retallick, 4 Matt Symons, 3 Ben Tameifuna, 2 Mahonri Schwalger, 1 Jamie Mackintosh.
Substitutes: 16 Rhys Marshall, 17 Pauliasi Manu, 18 Josh Hohneck, 19 Michael Fitzgerald, 20 Tevita Koloamatangi, 21 Brad Webber, 22 Robbie Fruean, 23 Asaeli Tikoirotuma
Stormers
15. Jaco Taute, 14. Kobus van Wyk, 13. Jean de Villiers (captain), 12. Damian de Allende, 11. Gio Aplon, 10. Demetri Catrakilis, 9. Nic Groom, 8. Duane Vermeulen, 7. Schalk Burger, 6. Deon Fourie, 5. De Kock Steenkamp, 4. Ruan Botha, 3. Brok Harris, 2. Tiaan Liebenberg, 1. Steven Kitshoff
Substitutes: 16. Stephan Coetzee, 17. Oliver Kebble, 18. Frans Malherbe, 19. Siya Kolisi, 20. Nizaam Carr, 21. Louis Schreuder, 22. Peter Grant, 23. Sailosi Tagicakibau