Rasul set up the business in July 2009 to provide a "fun and enjoyable" source of information on movies, gadgets, phones, MP3 players, computers and games consoles.
The site, which hit financial break-even in June, currently has 80,000 unique visitors per month.
Rasul financed Geeks in its first year through cash and the provision of other resources such as office space. Millar is now set to move Geeks' editorial centre to London, where Bishop is already based.
Bishop is founder and managing director of 7thingsmedia, the London-based digital media agency. He was brought in during the months after Geeks' launch to lead the site's commercial development.
The buyers have paid Rasul a small upfront fee, with the remainder of the consideration to be paid in the coming 3 to 4 years, dependent upon future performance. Rasul, who had little operational input into Geeks, said Millar and Bishop had ambitious plans for the online magazine going forward.
"They are hoping that profits in year three will be somewhere in the region of a quarter of a million," he said.
Rasul features in the online version of Dragon's Den, and has an estimated wealth of £80m.