Griffin sent Marvin Williams and then Horford to the floor with hard fouls in the final seconds. The last was the most costly, though Clippers coach Vinny Del Negro argued against the flagrant 1 ruling.
Jamal Crawford had 34 points, 16 in the third quarter. Atlanta's two All-Stars had big games: Horford had 23 points and 12 rebounds, and Joe Johnson added 17 points, nine assists and nine rebounds.
Baron Davis had 22 points and 13 assists for Los Angeles. Griffin, the NBA's first rookie All-Star selection since Yao Ming in 2003, had 19 points and 11 rebounds.
Eric Bledsoe made two free throws after he was fouled by Crawford with 11.5 seconds left to give the Clippers a 100-99 lead. The Clippers' Randy Foye then blocked a shot by Johnson and the ball bounced out of bounds as the two players fought for possession.
The officials went to the TV replay monitor to determine possession and ruled a jump ball with 4.2 seconds remaining. Johnson tipped the ball to Williams, who was sent crashing to the floor on a foul by Griffin, giving possession to the Hawks with 3.3 seconds to go.
The pass went to Horford, who drove to the basket and was leveled on another hard foul by Griffin. Each player was left sprawled on the floor for a couple minutes.
Horford, holding his back in pain, remained in the game to shoot the two decisive free throws.
The Clippers' front line caused problems early before Crawford had 16 points in the Hawks' 26-6 run to finish the third quarter. After trailing by eight, the Hawks led 79-67 at the end of the quarter.
Williams returned from a two-game suspension for a fight with New York's Shawne Williams. Marvin Williams, the regular at small forward, didn't start as Hawks coach Larry Drew went with his big lineup. Jason Collins joined Al Horford and Josh Smith on Atlanta's front line.
The 7-foot Collins wasn't enough against the Clippers' inside game, led by Griffin, Ike Diogu and DeAndre Jordan.
Jordan used a quick move to shoot past Collins for a jam on the Clippers' first two baskets, setting the pace for an emphasis on inside production.
Diogu had 14 points, including 12 in only 8 minutes in the first half.
Notes: Davis (back spasms) was cleared after pregame warmups. ... The Hawks are 5-5 against Western Conference teams. ... Los Angeles opened an 11-game road trip, including eight games before the All-Star break. The Clippers fell to 3-16 on the road.