The 2004–05 Big East Conference men's basketball season was the 26th in conference history, and involved its 12 full-time member schools.
Boston College and Connecticut were the regular-season co-champions with identical records of . Syracuse won the Big East tournament championship.
Rankings.
Connecticut and Syracuse were ranked in the Associated Press poll Top 25 all season, with Syracuse reaching No. 3. Boston College, Notre Dame, Pittsburgh, Villanova, and West Virginia also appeared in the Top 25, with Boston College also reaching No. 3. Boston College, Connecticut, Syracuse, and Villanova all finished the season as ranked teams.
Postseason.
Big East tournament.
Seeding.
St. John's was ineligible for the Big East tournament because of sanctions against the program. The other 11 teams were seeded in the tournament based on conference record and tiebreakers. The No. 6 through No. 11 seeds played in the first round, and the No. 1 through No. 5 seeds received byes into the quarterfinal round.
Seeding was and 
NCAA tournament.
Six Big East teams received bids to the NCAA Tournament. Pittsburgh and Syracuse lost in the first round and Boston College and Connecticut lost in the second round. Villanova was defeated in the regional semifinals and West Virginia in the regional finals.
National Invitation Tournament.
Two Big East teams received bids to the National Invitation Tournament, which did not yet have seeding. They played in two of the tournament's four unnamed brackets. Notre Dame lost in the first round and Georgetown in the quarterfinals.
Awards and honors.
Big East Conference.
Player of the Year:
Defensive Player of the Year:
Co-Rookies of the Year:
Co-Most Improved Players:
Coach of the Year:
All-Big East First Team
All-Big East Second Team:
All-Big East Third Team:
Big East All-Rookie Team:
All-Americans.
The following players were selected to the 2005 Associated Press All-America teams.
Consensus All-America First Team:
First Team All-America:
AP Honorable Mention