Chris Kaman had 21 points and 10 rebounds for the Clippers, who are winless in five games since Kim Hughes replaced Mike Dunleavy as head coach. Rasual Butler and Eric Gordon each had 18 points.
Point guard Steve Blake made his Clippers debut, following the trade Tuesday that sent Marcus Camby to the Trail Blazers in exchange for Blake and Travis Outlaw.
Blake had nine assists and three points in 33 minutes and was 1 for 6 from the field while starting for Baron Davis, who missed his first game of the season because of a sore lower back that plagued him during Tuesday night's 109-87 loss at Portland.
Less than an hour before tipoff, Los Angeles acquired Drew Gooden from Cleveland in a three-team trade that sent Al Thornton to Washington and Sebastien Telfair to the Cavaliers. The Wizards had acquired Gooden on Saturday in a trade with Dallas.
Horford, who made 12 of 15 shots, paced Atlanta to a 56-44 halftime lead with 17 points. He scored seven of them during a 17-6 run, capping it with an assist on a fastbreak layup by Josh Smith that extended the Hawks' lead to 54-38 with 2:48 left in the second quarter.
The Clippers got as close as 81-75 on a 3-pointer by Butler with 3 seconds left in the third quarter, but the Hawks opened the fourth with a 14-2 run to open up a 95-78 lead. Smith capped the rally with an alley-oop dunk off a feed from Jamal Crawford with 8:08 remaining, and the Clippers got no closer than 16 points.
Despite coming in cold to a new team, Blake had four assists in the first 6 1-2 minutes - three of them in a 1:34 span to set up an 18-footer by Kaman, a short jumper by Eric Gordon and a 3-pointer by Butler. In the second quarter, Blake threw a perfect alley-oop lob above the rim that DeAndre Jordan slammed home to trim Atlanta's lead to 37-32 with 7:37 left in the half.
Crawford, playing with a sore left shoulder, scored 12 points and is 28 away from 10,000. Crawford has played 648 games in the NBA, the most by any active player who hasn't gotten to the playoffs. But that should change this season, with the Hawks holding the third-best record in the Eastern Conference (34-18).