After a stellar season which saw him win 19 Group Ones, the 49-year-old arrives in Hong Kong still at the top of his game.
He has not taken part in Wednesday's event since 2011 - when he claimed the title.
Dettori said: "It's really exciting to be back. It's a great atmosphere at Happy Valley - and this series is always challenging, taking on the best around this unique track."
Oisin Murphy is also taking part, fresh from being crowned champion in Britain for the first time.
He said: "I'll be studying the races tonight and watching the videos.
"I'm glad to be back here. I first came in 2016 and I've been back each year since. I've learned a lot here, watching guys like Zac (Purton) and Joao (Moreira)."
Silvestre de Sousa, whose title Murphy claimed, is hoping to defend his IJC crown but admits to "feeling a lot of pressure" this year.
"There's a lot of superstars here," he said.
"I'm just proud and happy to be a part of it - and I just hope I get lucky."
Yuga Kawada makes his debut in the event, having won the World All-Star Jockeys champion in Japan.
He said: "I'm honoured to join the IJC with all the world's top jockeys. The line-up is so amazing.
"This is my first time to ride at this sharp and tricky course, but I will do my best."
Ryan Moore, Moreira, Vincent Ho, Karis Teetan, Colin Keane, James McDonald, Pierre-Charles Boudot and Purton are also competing.
Related horse racing links