The Citroen driver, who is planning to compete in only a handful of rallies next year as he turns his attention to the world touring car championships, beat Jari-Matti Latvala in a Ford Focus with his Citroen teammate Mikko Hirvonen taking third.
This was Loeb's 76th career win, the French rally legend coming in seven seconds clear of Latvala, who claimed third in the overall drivers' standings, with Hirvonen 1min 46.8s adrift.
Results of the season-closing Rally of Spain on Sunday:
1. Sebastien Loeb (FRA/Citroen DS3) 4hr 14min 29.1sec, 2. Jari-Matti Latvala (FIN/Ford Fiesta) at 7s, 3. Mikko Hirvonen (FIN/Citroen DS3) 1:46.8, 4. Mads Ostberg (NOR/Ford Fiesta) 1:56.4, 5. Jarkko Nikara (FIN/Mini Cooper) 16:07.9, 6. Craig Breen (IRL/Ford Fiesta S2000) 18:10.4, 7. Chris Atkinson (AUS/Mini Cooper) 19:14.7, 8. Per-Gunnar Andersson (SWE/Proton) 20:16.1, 9. Daniel Sordo (ESP/Mini Cooper) 25:40.6, 10. Evgeny Novikov (RUS/Ford Fiesta) 26:05.6, 11. Petter Solberg (NOR/Ford Fiesta) 26:23.7, 12. Thierry Neuville (BEL/Citroen DS3) 26:49.4
Special stage winners:
Sordo (SS10, SS11, SS13, SS14, SS15, SS18), Latvala (SS1, SS7, SS16, SS17), Loeb (SS3, SS5, SS8, SS9), Tanak (SS2, SS12), Ostberg (SS2), Novikov (SS4), Hirvonen (SS6)
Overall standings
Drivers
1. Sebastien Loeb (FRA) 270 pts - champion, 2. Mikko Hirvonen (FIN) 213, 3. Jari-Matti Latvala (FIN) 154, 4. Mads Ostberg (NOR) 149, 5. Petter Solberg (NOR) 124, 6. Yevgeny Novikov (RUS) 88, 7. Thierry Neuville (BEL) 53, 8. Ott Tanak (EST) 52, 9. Martin Prokop (CZE) 46, 10. Sebastien Ogier (FRA) 41, 11. Dani Sordo (ESP) 35, 12. Nasser Al-Attiyah (QAT) 28, . Chris Atkinson (AUS) 28
Teams
1. Citroen Racing 453 pts - champions, 2. Ford Motorsport 309, 3. M-Sport (Ford) 170, 4. Adapta WRT (Ford) 81, 5. Citroen Junior Team 72, 6. Qatar WRT (Citroen) 71