Chiefs controversially unveiled the jersey, not the player, last week (the jersey even has a Twitter account), but the deal was finally sealed on Sunday, after months of speculation.
"It has always been my wish growing up in Tshiombo, that one day I would play for Kaizer Chiefs and I never had any doubt that it was going to happen this season," Mathoho tells Chiefs' official website.
"I sat down with Bloemfontein Celtic and made my intentions clear about joining a club of my choice, Kaizer Chiefs.
"I would like to take this opportunity to first thank the management at Bloemfontein Celtic and the fans in the manner they accepted me and supported me during my stay at the club. I am also grateful for the contribution they have made in me as a player."
Mathoho says his decision to join Amakhosi was not only influenced by his family; his national teammates had a lot to do with it as well.
"I love Kaizer Chiefs and I wanted to come here to continue with my career," 'Tower' says.
"I am happy in the manner in which the club is run, also some of my teammates in the national squad, Shabba [Siphiwe Tshabalala] and Itu [Itumeleng Khune] told me about how professionally the club is run.
"At home they support Kaizer Chiefs, but my father told me that he will support me wherever I play and whatever decision I make. They are all delighted that I have chosen Chiefs."