The club from the Mediterranean resort had been co-managed on a temporary basis by their star striker, the former Cameroon international Samuel Eto'o, after the departure of Yusuf Simsek last month.
Described as the right-hand-man of Mourinho, Morais worked as an assistant to his fellow Portuguese in almost all of his key assignments including at Porto, Inter Milan, Real Madrid and Chelsea.
Along with several other of Mourinho's loyal backroom staff, Morais left Chelsea in December after the sacking of the manager as a result of a dire first half to the season.
Morais, 50, signed a one-and-a-half year contract at a ceremony with Antalyaspor chairman Gultekin Gencer, the club said in a statement on their website.
Antalyaspor were promoted to the Super Lig at the end of last season but their current mid-season position of 11th is far from sufficient to satisfy the team's lofty ambitions.
"The first aim to lift our position in the league. This year the club is celebrating its 50th birthday. We need to present something new to our fans as a gift," said Morais.
Morais had also been linked with the vacant manager's job at Premier League side Swansea City.