The win snapped a five-game losing streak for the Titans (3-6), as Horne scored a career-high 21 points on 9-of-11 shooting from the floor, including a perfect 2-of-2 mark at the charity stripe. The senior added seven rebounds and two blocks in the contest.
McClellan poured in 13 points and grabbed seven rebounds for Fullerton, as the Titans were able to erase a halftime deficit for the first time this season.
Senior Michael Williams was the third Titan to reach double figures, adding 12 points and a game as well as career-high six assists.
Fullerton outscored Pepperdine 48-34 in the paint, and outrebounded the Waves 42-29. Another key statistic was Fullerton's ability to shoot a perfect 9-for-9 from the free-throw line in the second half.
In addition, the Titans shot 56.7 percent from the floor (17-of-30) in the second half as Horne scored 15 of his 21 points in the game's final 20 minutes.
After Pepperdine (5-4) closed the first half on a 14-8 run, the Titans returned the favor and opened the second period on a 9-3 run to claim a 41-40 lead with 16:45 remaining after Sheldon Blackwell sank a short jumper.
Pepperdine would hold the lead just once more – after a Brendan Lane layup – before a McCellan lay-in put the Titans up for good, 43-42, with 15:32 to play.
Pepperdine remained within striking distance for the majority of the second half, but James Johnson gave the Titans their biggest lead of the game at the time, 56-49, scoring an inside bucket with 10:36 left to play in the game.
The lead grew to double digits after a basket interference call plus the foul put McClellan at the free-throw line to convert the three-point play as the Titans led 66-55 with 3:59 to go.
The Titans shot 50.8 percent (30-of-59) from the floor and held Pepperdine to 40.0 percent (24-of-60).
Fullerton trailed 37-32 at the break after Pepperdine ended the half on a 14-8 run, turning Fullerton's last lead, 24-23 with 7:46 to play, into a five-point halftime deficit.
Joe Boyd led the Titans with eight first-half points, but Fullerton couldn't contain Lane, who totaled 13 points on 6-of-8 shooting in the first 20 minutes.
Lane finished the game with 24 points on 10-of-17 shooting, while Jeremy Major added 10 points for Pepperdine.
In the first half, the game featured five tie scores and 10 lead changes.
Fullerton jumped out to an early 12-6 lead following a Blackwell jump shot, but Pepperdine's 9-0 run gave the advantage back to the Waves.
Fullerton shot 44.8 percent from the floor in the first half, but was plagued by a .462 percentage (6-of-13) from the free-throw line.
The Titans return to action Saturday hosting Seattle at Titan Gym with tip-off scheduled for 6:00 p.m.
Notes: The all-time series between the Titans is even at 11-11 and the win was Fullerton's fifth in Malibu…the Titans have shot over 50.0 percent from the floor in each of their three wins this season…Fullerton erased a halftime deficit for the first time this year…head coach Dedrique Taylor used his fifth starting lineup of the season: Sheldon Blackwell, Michael Williams, Alex Harris, Joe Boyd, Marquis Horne …Michael Williams reached double figures (12) for the ninth consecutive game… Alex Harris left the game with 1:06 remaining in the second half with an injury.