Manyama, who claimed the accolade for a third time this season, has been key to City's rise to the summit and their Telkom Knockout triumph, providing 12 goals and five assists.
Mosimane was rewarded for Downs' unbeaten run last month, which included the 6-0 thumping of Orlando Pirates and a 2-0 win over title rivals Bidvest Wits.
"It is an honour to come here again, I could not have done this without my team Cape Town City," said Manyama on receiving his prize.
"I would be more happier if we won team of the season first before the player of the season award," added the Bafana Bafana winger.
Mosimane was likewise humbled by the recognition.
"I would like to thank everyone who has played a role in this. I am humbled."