Dieng, a 6-foot-10 center, showed confidence in his jumper and the result was 10 of 11 shooting from the field. The junior also grabbed eight rebounds and blocked two shots.
Russ Smith added 19 points and Luke Hancock made three 3-pointers and finished with 13 points as the Cardinals (22-5, 10-4) won their third in a row to draw within a half game of Big East Conference leaders Syracuse, Georgetown and Marquette, all of whom played later Saturday.
Against Seton Hall, Louisville wanted to firm up its game ahead of an important stretch run including next week's showdown at No. 8 Syracuse. The Cardinals succeeded on just about every count, forcing 21 turnovers including 12 steals and shooting 26 of 57 (45.6 percent).
Aaron Cosby scored 14 second-half points for 17 to lead Seton Hall (13-15, 2-13), which dropped its ninth straight.
Eugene Teague added 16 points, Brian Oliver 12 and Fuquan Edwin 11 for the Pirates, who shot 23 of 52 (44 percent).
Louisville was playing six days after one of its best defensive efforts, a 59-41 win at South Florida in which the Cardinals held the Bulls to 13-of-53 shooting (24.5 percent) and allowed just three more points than the previous meeting.
That effort followed coach Rick Pitino's recent practice shift toward players working on their respective strengths, which also included offense. Dieng, for example, has focused on shooting jumpers, which has been effective for him when used.
The individualized effort clearly benefited Dieng, who sank two jumpers from the foul line along with a tip-in to give Louisville an 8-2 lead. Oliver, Cosby, Edwin and Karlis Haralds combined for four jumpers including three from beyond the arc, keying Seton Hall's 17-9 spurt to put them up by two.
Seton Hall's zone defense also stifled Louisville during that run, no doubt due to coach Kevin Willard's familiarity with Pitino's system as a former Cardinals assistant.
Louisville snapped out of it and took over from there, closing the half with a 23-7 run over the final 9:40 of the half for a 40-26 lead at the break. Four 3-pointers helped - notable for a team hitting just 32 percent from beyond the arc coming in - while Dieng added a couple more soft jumpers en route to a 10-point half.
The Cardinals made five of seven from long range and 13 of 28 overall from the field (46 percent), while their signature defense made seven steals and forced 11 turnovers leading to 10 points. Seton Hall hit just 10 of 26 field goal attempts.
Injuries have plagued the Pirates, with Brandon Mobley's season-ending shoulder surgery being the most recent. And that lack of depth became a factor as they fell behind by 19 several times in the second half.