Folau scored a try with his first touch of the game and had French supporters on their feet every time he touched the ball in Perpignan.
The controversial 30-year-old's religious views on homosexuality saw him banned by Australian rugby union but he hit the ground running in Super League. Ten years after his rugby league career began Down Under he returned to the 13-a-side code as if he had never been away.
The world's media descended on Stade Gilbert Brutus but any attempt by Castleford to steal the headlines were thwarted as early as the second minute when former NRL star James Maloney found a gap for Sam Tomkins to stride under the posts.
Then Folau struck when he collected a high kick from Josh Drinkwater to touch down and Maloney's conversion made it 12-0 with just six minutes on the clock.
Castleford winger Derrell Olpherts hit back with an 80-metre dash from a clever in-goal collect and re-start by scrum-half Danny Richardson, who then converted Olpherts' try from in front of the posts.
A Maloney penalty in front of the posts after 24 minutes put Les Dracs back on track and 10 minutes from half-time, Tomkins fielded a high kick 10 metres from his own line, found winger Fouad Yaha who raced 60 metres and released centre Samisoni Langi for a stunning try.
Castleford hit back just before half-time, two successive penalties putting centre Cheyse Blair in space on the right, Richardson's conversion making it 20-12 at half-time.
The Dragons withstood early pressure from the visitors after the break with some solid defence and with Maloney marshalling the troops, Catalans capitalised on a penalty 20 metres out.
The ball was moved to the left where Tomkins twisted and turned over the line, Maloney scraping the post with his conversion to put the Dragons in the driving seat at 26-12.
Olpherts was sin-binned for delaying a quick re-start from Tomkins and 12-man Castleford struggled to contain the Dragons, despite Richardson's best efforts.
When Tomkins released Langi, it was Yaha who again capitalised with a try on the left, too far out for Maloney to add the conversion.
At 30-12 the Dragons sensed victory but Richardson's 40-metre dash up the middle of the pitch and pass to winger James Clare clawed back some points for the Tigers, the scrum-half adding the conversion to make it 30-18.
Boosted by the return of Olpherts from the sin-bin, Castleford made the most of a ball-spill by Benjamin Garcia and pressed hard on the Dragons line but could not find a way through some resolute defence.
An attempted drop-goal by Tomkins was wide of the mark but when Sam Kasiano returned to the fray, Catalans pushed for the finish. Man of the match Tomkins again was chief tormentor with a late try that bamboozled the Tigers defence and Maloney's conversion wrapped things up at 36-18.