Smith drained 10 of his 15 shots overall while also grabbing 13 rebounds and handing out six assists for the Hawks, who won for the second time in three games.
Al Horford contributed a double-double of 21 points and10 rebounds in Atlanta's victory.
The Mavericks fell for first time in three games despite 24 points from Dirk Nowitzki.
O.J. Mayo added 19 points in the loss.