Kentucky (4-0) moved up from No. 2 after top-ranked Duke lost to Kansas last week in the Champions Classic at Madison Square Garden.
Meanwhile, the Cats recorded decisive wins over No. 13 Michigan State (69-48) and Duquesne (93-59).
UK received 42 of 65 first-place votes in the poll.
Defending national champion Villanova (5-0) moved up one spot to No. 2 and also picked up 21 first-place votes following a week which saw Jay Wright's Wildcats pick up four wins.
Indiana (3-0) moved up to No. 3 and received two first-place votes. The Hoosiers were followed by North Carolina, Kansas, Duke, Virginia, Arizona, Xavier and Louisville to round out the Top 10.
The Cats will be playing the No. 4 Tar Heels and No. 5 Jayhawks later this season. They'll also face No. 14 UCLA.
No other SEC team was ranked this week, although Florida did receive votes.
Kentucky has spent 34 weeks at No. 1 under Calipari during his time in Lexington. The Cats have been the top-ranked team for at least one week in 2009-10, 2011-12, 2013-14, 2014-15, 2015-16 and 2016-17.
Historically, it marks the 123rd week atop of the AP Top 25 poll for UK. Only UCLA (134) and Duke (129) have more weeks with the No. 1 ranking.