The Qatari, who won the second stage but then suffered a mechanical failure on day four, took the win in Copiapo in the car category in a time of three hours, 26 minutes 57 seconds.
He finished seven and a half minutes ahead of Hummer team-mate Robby Gordon in second spot, with third place going to France's Stephane Peterhansel in his Mini a further 23secs back.
Dakar legend Peterhansel remains in first spot on the overall leaderboard, 11:22 ahead of Poland's Krzysztof Holowczyc with Gordon in third spot. Al-Attiyah is in sixth place, 42:54 behind the leader.
In the bike category, another reigning champion was also victorious as Spaniard Marc Coma took the seventh stage honours.
He finished 2:03 in front of KTM team-mate Cyril Despres, although the Frenchman remains in the overall lead, 7:48 ahead of Coma.
Sunday is a rest day.