The Bobcats were coming off 114-69 loss — the worst in franchise history — on Monday at Oklahoma City, but they led at the 2:34 mark of the second quarter when Michael Kidd-Gilchrist's layup ended an 18-2 run that put Charlotte up 42-35.
By the 7:11 mark of the third, the Hawks led for good after Horford's three-point play made it 52-51.
Smith, who finished with a game-high 13 rebounds, was the catalyst for most of the third, scoring 13 points on 5-for-7 shooting and getting four rebounds, two steals and a blocked shot.
"Just being active, being around the basketball, creating plays for myself and others, being patient and then when the opportune time comes for me to be aggressive, I took advantage of it," Smith said. "It wasn't necessarily play calls. It was just me being patient and playing to the flow of the offense."
Kemba Walker scored 15 points and Brendan Haywood pulled down 11 rebounds for the Bobcats.
Horford is pleased that the Hawks' reshaped roster, which includes the additions of veterans such as Williams, Kyle Korver, Devin Harris, DeShawn Stevenson and Anthony Morrow, isn't playing like recent Atlanta teams that often squandered games against less-talented opponents.
"These games, in the past, one of them we would've dropped if we didn't come out with enough energy and little things like that," Horford said. "I think this year we're doing a good job even though it's closer than we would like. But we're getting the wins."
NOTES: Korver left with back spasms in the third and didn't return. ... Bobcats C Bismack Biyombo, returning after missing the last two games with a bruise on his lower left leg, finished with six points and eight rebounds in 27 minutes. ... Harris, playing for the first time since spraining his left big toe in last Friday's win at Charlotte, had seven points and four assists.