The England midfielder resisted an offer from Tottenham and signed a new deal to 2028 after a chat with Marinakis.
"I’m delighted,” Gibbs-White told the club. “So thank you to Mr Marinakis for believing in me.
“I feel like we’ve been on a rollercoaster of a journey, but I felt the love instantly from the very first moment I stepped through the doors.
“We’ve had difficult times but we’ve had a lot of highs. Last year was really exciting. We got to showcase what we’re about and what we’re trying to build as a team. Mr Marinakis is the base of that.
“Mr Marinakis is the main reason for that (ambition). We’ve built that culture inside the dressing room. I feel like that’s driven us all the way through.
“The manager’s been incredible since he’s come in. The fans have been amazing from the very first moment I joined.
“To give them back European football, it’s something as a dressing room, as a team, as a club, we’re all really proud about.
“They’re the ones who deserve it the most because they’re the ones who pay their hard-earned money to show up at the weekends, come and watch us play, support us and cheer us.
“They’re the ones who deserve it the most and we’re happy we’re able to give back to them.”