It was at an early age Ambrose showed signs of motor racing ability and won four Tasmanian Junior karting titles before commencing senior competition at 16 years old. Leaving Australia to chase the elusive Formula One dream in England in 1996, he learned quickly and won regularly, but despite his success, Ambrose needed further financial backing to continue chasing his elusive F-1 dream, so it was time to come home to Australia.
The Stone Brothers Racing Team and Ford signed Ambrose in 2001 to compete in the V8 Supercar series, and he backed up their confidence by finishing eighth during his rookie season. The 2002 season started with a bang with Ambrose snaring the pole position at Phillip Island before recording his debut race win the first race of the season.
With a new BA Falcon, Ambrose gave the Ford team a great start to the 2003 season with victory in the first race of the Clipsal 500 in Adelaide. He followed this fantastic start with a third career win at Eastern Creek Raceway where he led Ford home to a memorable 1-2-3 at the Sydney track; Ford's first clean sweep of the podium since Eastern Creek 1997 and Ambrose’s first win for the season. After 13 rounds in the 2003 V8 Supercar Series, Ambrose was presented with the driver’s series trophy, 102 points clear of second place.
In 2004, Ambrose continued to shine. He claimed three pole positions and five round wins and went into the final round at Eastern Creek with a virtually unbeatable lead. In the end, he collected his second championship in the opening Saturday night race and then went on to clean-sweep the round in record-breaking style in his Pirtek Falcon.
He started 2005 the way he ended 2004 - with a clean sweep of the opening round in Adelaide. He remained in the championship lead until after round 11 at Bathurst when he was taken out of the race; he settled for second in the final standings.
Ambrose once again left his native Australia to chase a dream of racing in NASCAR.
Ambrose brought his success into NASCAR when he began competing in the Camping World Truck Series in 2006 and then the Nationwide Series in 2007.
In 2006, Ambrose scored two top-five finishes and four top 10s in 22 starts in the truck series.
In his first season in the Nationwide Series, at age 30, Ambrose won one pole, at Memphis Motorsports Park on October 27, while at the same time, gained his first top-five of the season. Marcos also totaled six top-10s and finished out his rookie season eighth in points standings, driving the No. 59 Kingsford Ford.
In 2008, Ambrose again ran a full Nationwide schedule, while making 11 starts in the NASCAR Sprint Cup Series. He had the most successful weekend of his stock car career at Watkins Glen, when he scored his first victory in the Nationwide Series and followed it up with his first Cup top five - a third-place finish - in the Sunday Cup event.
2009 was a good season for Ambrose. He posted a career high 4 top 5s and 7 top 10s and was able to prove that he was more than just a road racer with a 4th place finish at a restrictor-plate track (Talladega) and a 3rd place finish at a short track (Bristol). He also set a career high 18th in the points race.
