The Irish mixed martial arts fighter hailed the “die hard support” after a McGregor-inspired banner was unveiled in the safe standing section of Celtic Park.
It read “We’re not here to take part, we’re here to take over” along with a likenesses of Brendan Rodgers, Scott Brown and Kieran Tierney.
The phrase is one of the more famous quotes from the loquacious Irishman, who takes on boxer Floyd Mayweather next weekend.
He wrote on Twitter: “Celtic Football Club STAND UP!!! This is what die hard support from your fans looks like! What a sight! What a team! Thank you all!”