Arcidiacono had six points and two assists in the extra period. He hustled for a loose ball with 37.7 seconds left that allowed Villanova coach Jay Wright to call a timeout and avoid a turnover.
James Bell, who finished with 30 points, followed with two free throws to make it a three-possession game for the Wildcats (17-2, 6-1 Big East).
Todd Mayo had 18 points, including the last 10 in regulation, for Marquette (11-9, 3-4) to help force overtime at 77-77.
A layup by Villanova's Tony Chennault with 1 second left in regulation was waved off by the officials after Steve Taylor, Jr., drew a charging foul.
Villanova snapped Marquette's 20-game winning streak in home conference games.