The Big Lemon was founded by Tom Druitt in 2007.
After gaining an operator licence, the first public transport route was launched on 1 September 2007. Route 42X originally operated from Brighton Station to Falmer Station, with hopes to expand the operation with more routes. After lower than expected passenger numbers, and competition from Brighton & Hove, the company scaled down the level of service, re-launching it in January 2008, and to reconsider its operating model. From 7 to 29 January 2008, the service operated on a reduced frequency, ending once the original route registration expired after the mandated period.
On 17 March 2017, it was announced that Norman Baker, the former Liberal Democrat MP and Parliamentary Under Secretary of State for the Department for Transport, had been appointed managing director of the Big Lemon.
On 17 September 2017 , The Big Lemon took over routes 16, between Portslade and Hangleton, 47, between Brighton station and East Saltdean, 56, between Knoll estate and Patcham , 57, between Brighton station and East Saltdean and 66 which goes in a circular route around Portslade and Hangleton.
Route 42/42A/N42 was The Big Lemon's first public bus service, originating from its service 42X. Service 42 operated from Churchill Square to Sussex University via Lewes Road. During the evenings the route number changed to 42A and served West Street. It would later be renumbered N42. The N42 charged higher fares as it operated from 00:00 – 04:00. In 2011 the company renumbered routes 42A and N42 to 42.
As at September 2017 The Big Lemon operate six services. Additionally they operate a shuttle bus for Brighton Metropolitan College Coaches run on biodiesel that is refined from waste cooking oil.. Buses run on solar power and diesel.
The Big Lemon operates a fleet of Mercedes-Benz O814D and Optare Solo buses. The company is also temporarily using six enviro 200 and one Volvo B7TL Plaxton President until new solar powered buses are delivered to operate the new routes. The company also has five Volvo B10M coaches, three with a Van Hool body, one with Jonckheere and one with Plaxton Premiere, as well as an electric minibus.
The number of vehicles in total is 22.