All three started the series-clinching third Test in Sydney and the trio are now beginning their new adventure in France.
Sexton made the journey last Wednesday and revealed Toulouse, Clermont Auvergne and RC Toulon were interested in securing his signature.
But he chose Racing for their personal approach and the opportunity to play alongside the fellow recruits that he got to know so well in Oz.
"I didn't know Racing," said Sexton.
"They contacted me just like Toulouse, Clermont and Toulon did. But this club really gave me that the impression that I counted for them.
"They advised me to come here, saying they have a very ambitious team. I met the new coaches and I like them.
"Then I learned that (Jamie) Roberts and (Dan) Lydiate were coming too and that reinforced my choice."
It is reported that the Irish fly-half will pocket €700,000 a year at Racing but he insists the financial rewards were not the only factor behind his decision.
And he believes the big-spending club have the talent to challenge for both the Top 14 title and Heineken Cup.
"Of course money was one of the reasons that made me come here but it wasn't the only one," added Sexton.
"I'm going to give everything for Racing and I'm very proud to wear their colours.
"I have a lot of things to prove on the pitch. If people see my involvement, they'll know that I'm not only here for the money.
"Maybe we can win silverware. Why not? We have the players, the staff and the infrastructure to do it. It's possible"
The 28-year-old is set to make his competitive debut for the club against Brive in La Rochelle on August 17th.