The Western Province Rugby Union on Wednesday officially announced the signing of the 23-year-old from their northern rivals. He will join his new team later this year after completing Currie Cup duties with the Blue Bulls.
Mbonambi was unhappy in Pretoria after playing second fiddle to Callie Visagie all season, and when the Bulls also showed interest in the Cheetahs' Adriaan Strauss, he felt out of favour, especially with Bandise Maku also in the frame.
It is believed he was not given the amount of game time promised in this year's Super Rugby competition.
It is however no certainty that Mbonambi will get more game time in the Cape, despite the departure of Deon Fourie to Lyon in France.
The 23-year-old Mbonambi, a former SA Schools hooker, showed glimpses of his potential when he got a chance in Bulls colours and will certainty add depth in the position for the Stormers.
However, exactly how much game time he gets in the Cape remains to be seen. The Stormers still have two very capable hookers in Tiaan Liebenberg and Scarra Ntubeni, while the young Stephan Coetzee has also displayed tremendous potential.
The 22-year-old Coetzee impressed this writer in an earlier game this season when he started against Springbok hooker Bismarck du Plessis as the Stormers stunned the Sharks 21-19 in Durban.
While there's no doubt Mbonambi will add depth to the hooker position, regular game time for the Stormers is perhaps no certainty...