After completing his M.S., Parsons began teaching GIS at the Kingston University. He continued teaching there until 1998. During his tenure, he is credited with having created the first online map of general election results of 1997.[10]
In 1998, he moved to Autodesk as an EMEA Applications Manager for the Geographical Information Systems Division. He joined Ordnance Survey in 2001 as the organization’s first Chief Technology Officer and played an instrumental role in moving the course of the organization from mapping to geographical information and went on to become the youngest director of IT.[11][12]
When Google Maps was launched in 2005, he described the event as ‘’In a few months Google Maps has done more to allow the individual to develop mapping based websites than the traditional GIS industry has done in 10 years.[13] However, in June 2005, he was one of the first observers of the typing error that Belgium had swapped places with Netherlands on Google Maps.[14]
Parsons left Ordnance Survey in December 2006 and he was offered a job by Google. Parsons began working at the London office of Google. He also set up his own company Open Geomatics, a strategic consultancy firm focused on the geospatial technology tracking and Neogeography.[15][16] In 2010, Parsons received an honorary PhD in Science from the Kingston University in recognition of his contributions to the field of GIS and to the university.[17]
Parsons oversaw the coordination of Google Maps and Historypin in 2012 in an initiative to recover lost photographs and document the Royal appearances of the Queen on an interactive map of the world provided by Google Maps.[18][19]
In December 2015, Parsons was invited to deliver a keynote address at the GSDI World Conference in Taiwan.[20][21][22]
Parsons is a member of the Board of Directors of the Open Geospatial Consortium.[23] and a fellow of the Royal Geographical Society, an Associate Fellow of the Royal Institute of Navigation and a professional member of the British Computer Society.[24]
In 2017 Parsons was appointed as Visiting Professor at University College London in the Department of Civil Environmental and Geomatic Engineering.[25]