The current featherweight champ, McGregor would become the first fighter to simultaneously hold multiple UFC titles -- and oddsmakers have already pegged him a small betting favorite.
McGregor (20-3) is set to open a -125 favorite over Alvarez (28-4), who comes back at -105. Odds were provided by Nick Kalikas of MMAOddsBreaker.com.
It is the sixth consecutive fight in which McGregor has opened as a betting favorite. He is 5-1 in those matches, with his only loss coming via second-round submission to Nate Diaz at UFC 196 in March.
"This is a near pick 'em fight," Kalikas told ESPN.com. "McGregor is phenomenal on the feet, especially early. His timing, power and precision should be enough to give him an edge in the standup, despite Alvarez being an excellent boxer. Alvarez should have a big edge on the ground, particularly because he has great ability to take the fight to the floor."
UFC officials confirmed the 155-pound bout on Monday. The title fight will actually mark McGregor's lightweight debut in the UFC. His first seven appearances in the Octagon were at 145 pounds, including a 13-second knockout over Jose Aldo to win the featherweight title last December. He is coming off back-to-back welterweight fights against Diaz.
"I expect two-way action on this fight, with early money coming in on McGregor, but Alvarez action should narrow the gap as the fight approaches," Kalikas said.