On June 28, 2007, Horford was selected by the Atlanta Hawks with the third overall pick in the 2007 NBA draft. On July 9, he signed his rookie scale contract with the Hawks. As a rookie in 2007–08, Horford was the only player unanimously selected to the NBA All-Rookie First Team; he was also runner-up for Rookie of the Year honors and was named Rookie of the Month on four occasions. He became the first Atlanta draftee to earn first team honors since Stacey Augmon in 1991–92. Horford averaged 10.1 points, 9.7 rebounds, 1.5 assists, 0.9 blocks, 0.7 steals and 31.4 minutes in 81 games (77 starts). The Hawks finished the regular season with a 37–45 record and entered the playoffs as the eighth seed in the Eastern Conference. In their first round match-up with the Boston Celtics, Horford helped the Hawks take the eventual champions to seven games, losing the series 4–3. In the series, Horford averaged 12.6 points and 10.4 rebounds per game.