According to the Cambridge News website in January 2002, Cambridge City's 16 year old Robbie Simpson was signed from Norwich City's youth setup and made his full debut for Cambridge City in Jan 2002 aged 16.. Originally a midfielder, Robbie has been converted into a centre forward.

On 2nd June 2006, Robbie moved across the city of Cambridge to join Rob Newman's Cambridge United.

In April 2007, speculation suggested that Norwich are one of three Championship clubs running the rule over Cambridge United striker Robbie Simpson who has hit 13 goals in his last 14 matches for the Nationwide Conference outfit alerting the likes of Ipswich Town and Leicester City along with Canaries manager Peter Grant. Robbie is due to sign for Coventyr on 1st July 2007 with the fee to be decided by tribunal as Cambridge boss Jimmy Quinn claims the two clubs are "a million miles apart" in their valuation of the player. On 9th July, the FA set compensation for the move. Coventry will pay £40,000 initially, with an overall fee of £130,000 possible dependent on appearances and a 5 percent sell-on clause agreed for the 22-year-old striker. This was blasted by Cambridge chairman Lee Power "But the biggest kick in the teeth is the sell-on of just 5%. I've never known such a low sell-on in my life; they're normally much higher - 15% or 20%. They know the lifeblood of any smaller football club is the sell-on in a case like this, and they've given the player away on our behalf for £40,000 and then given us nothing to look forward to in the future with the sell-on. It's an absolute disgrace and I'm livid. I don't know yet if there is an appeal process but we'll find out,"

During 2008/9. Simpson was used mainly on the right wing by Chris Coleman, after slipping behind Leon McKenzie, Leon Best, Freddy Eastwood and Clinton Morrison in the pecking order for striking spots. His cause was not helped last season by a thigh strain, but he still made 37 appearances and scored five goals from the flank as Coventry's play-off push never quite materialised

In June 2009, Simpson was rumoured to be part of a deal that would take Norwich's Sammy Clingan to the Ricoh Stadium. Knebworth-born Simpson is regarded as a target man and at 6ft 1in would probably fit Gunn's requirements for a big front man, after Carl Cort, Chris Killen, Alan Lee, Antoine Sibierski and Darel Russell tried with varying degrees of success last season. Instead Robbie signed for Lee Clark's Huddersfield for a sum reported to be £300,000

Simpson was loaned to Brentford for the 2010-11 season on 6th August 2010, making 27 league appearances and scoring 4 goals.

Simpson joined Oldham Athletic on loan on 10th September 2011. He made 14 appearances, scoring three times, before his loan ended on December 12, but Huddersfield allowed him to stay at Oldham in a training capacity. He rejoined Oldham on loan, until the end of the season, on 1st January 2012. The loan was made permanent on 30th January 2012.