The midfielder had already signed a pre-contract agreement with Hibernian and knew he had European football to look forward to with the William Hill Scottish Cup finalists next season.
But he played a big part in his last game for Saints by netting the opener in a 2-0 win over Motherwell yesterday as the Perth side beat Inverness to the final Europa League berth.
Craig said: "It is good that Hibs are in Europe next season as well so I'd be playing in it anyway.
"Since I signed the pre-contract, it was never going to change how committed I was to the club.
"Early doors, there were one or two shouts from the fans when things weren't going our way.
"That was to be expected but I think the majority of the fans knew what I was all about.
"And I am sure I have sent them home happy.
"I am just looking forward to joining Hibs in the summer.
"But getting back to back European trips for St Johnstone is a great way to leave because it is the best thing you can do without winning any of the cups."