Norway's Mikkelsen started the final day of the rally with a narrow two-second lead over his Volkswagen team-mate, who was recently crowned the world drivers' champion for the fourth straight year.
Ogier closed the gap to just 0.3 seconds at the midpoint of the dusty Bucca stage, the second of five stages on the final day. But the Frenchman then spun his Volkswagon Polo R near the finish and completed the stage 19.6 seconds slower than Mikkelsen, giving the Norwegian a commanding overall lead.
Mikkelsen began the rally in third place in the drivers' standings behind Ogier and Belgium's Thierry Neuville, hoping a win would lift him into second place and give Volkswagen its fourth consecutive one-two finish in its final championship. The company has said it will not compete in WRC again after this season.
Perfect ending for Neuville
But Neuville, driving a Hyundai i20, finished the race in third place, ensuring he'd remain in second overall in the drivers' standings.
“The plan was to try and win the power stage because I would like to try and beat Thierry for that second place, but I'm still happy about this,” Mikkelsen said. “It's been such a perfect end to the season... It's just sad to see this team and the car come to an end. I will miss them.”
Ogier and Mikkelsen now find themselves looking for new cars for next season, likely putting pressure on drivers on other teams.
Mikkelsen dominated Volkswagon's final rally, leading after all but one stage and overcoming a bizarre incident on the second day when his clutch and brake pedal became wedged together.
The race was also delayed on the 21st stage for almost a half hour when Eric Camilli rolled his Ford onto its roof, causing a fire to break out in the car. He retired from the stage but appeared unhurt.
Rally of Australia - Top 10
1. Andreas Mikkelsen (Norway) Volkswagen 2:46:05.700
2. Sebastien Ogier (France) Volkswagen +00:14.900
3. Thierry Neuville (Belgium) Hyundai +01:12.600
4. Hayden Paddon (New Zealand) Hyundai +01:26.700
5. Daniel Sordo (Spain) Hyundai +01:28.300
6. Mads Ostberg (Norway) Ford +01:41.500
7. Ott Taenak (Estonia) Ford +03:04.300
8. Esapekka Lappi (Finland) Skoda +07:32.300
9. Jari-Matti Latvala (Finland) Volkswagen +07:56.900
10. Lorenzo Bertelli (Italy) Ford +08:00.100
Original source: Volkswagen wins its last world rally event