The Irish (24-1, 12-0 Big East) have won a school record 20 consecutive regular-season road victories, including 16 straight in the conference.
Notre Dame's lone loss of the season was to No. 1 Baylor 71-63 on Dec. 5.
The Irish led by 19 at halftime and put the game away early in the second half as Notre Dame scored the first 12 points of the half to grab a 46-15 lead when Diggins scored on a layup. Diggins was the key to the spurt as she scored six points, including a steal and breakway layup.
Marquette could get no closer than 24 points the rest of the way.
Sarina Simmons scored 12 points and Arlesia Morse added 11 for Marquette (12-13, 4-8) as the Golden Eagles hit just 17 of 51 shots in the game and had 20 turnovers.
Diggins, who hit 10 of 21 shots, also had six assists and four steals. Kayla McBride added 12 points. Diggins' defensive rebound with 13 minutes left in the first half allowed her to become the first women's basketball player in Notre Dame history with 2,000 points, 500 rebounds and 500 assists in her career.
With her 23 points, Diggins also passed Katryna Gaither on Notre Dame's all-time scoring list. She now has 2,131 points, trailing only current Irish assistant coach Beth (Morgan) Cunningham, who scored 2,322 points during her career.
Marquette had its only lead of the game at 2-0, but the Irish then went on a 14-4 when Diggins hit a jumper with 14:57 remaining. Marquette hit just three of its first 16 shots and had four turnovers in the first eight minutes of the game.
The Golden Eagles narrowed the score to 25-15 with 5:59 remaining in the first half when Katherine Plouffee hit a jumper.
But that would be the last point Marquette would score in the first half as Notre Dame scored the next nine points to grab a 34-15 halftime lead as Diggins hit a 3-pointer with 56 seconds remaining.