Sirino, who will enter his 10th season in the South African Betway Premiership having also turned out for Mamelodi Sundowns, joins former Chiefs co-coach Khalil Ben Youssef at City.
The Uruguayan spent the last two seasons at Chiefs, making 61 appearances (27 starts) and scoring five goals. He helped them to the 2025 Nedbank Cup title.
“The Club would like to express sincere gratitude to Papi for his dedication and contribution over the past two seasons,” Chiefs said in a statement. “The experienced Uruguayan midfielder played a key role in helping Amakhosi achieve success since he arrived at the Club.
“We thank Gaston for his commitment and passion, as well as all the memories he leaves behind at Naturena.”
Former Orlando Pirates midfielder Goodman Mosele is also reported to be joining City, while the club confirmed the capture of ex-Chiefs striker Tashreeq Morris on Monday.
