Rutland Partners, whose other investments include Pizza Hut UK and Bernard Matthews, said it would look to build on Maplin's recent improved trading performance after sealing the acquisition from Montagu Private Equity.
Founded in 1972 as a small mail order business, South Yorkshire-based Maplin now has 210 stores in the UK and Ireland and generates revenues of £220 million, up from £100 million when Montagu bought the business in 2004.
After a challenging few years, a new management team put in place in 2012 and led by John Cleland has refreshed stores, invested in a new web platform and refocused the business on innovation and 'first in, last out' product ranges.
Maplin has also been repositioned as a source of expertise for those who want to use electronics but need greater technical help and advice.
Outgoing chairman John Lovering said: "The team Montagu recruited, led by John Cleland, has done an excellent job.
"Personally, I think Maplin is on the threshold of a great period in its history. It is now time for a new shareholder to take the business forward, building on the strong foundations laid."
Current trading is said to be strong, with underlying earnings back in growth and like-for-like sales showing high single digit growth.
Rutland focuses on businesses headquartered in the UK worth between £20 million and £150 million. It also owns equipment hire firm Brandon Hire.
Managing partner Nick Morrill said: "We are delighted to be able to invest in Maplin and recognise the great progress made by management so far in the recovery of the business but more importantly the potential still to be unlocked."
Montagu bought Maplin in September 2004 from previous buyout firm Graphite Capital and management.
Montagu's past investments include hair products business ghd and Quorn. It is believed to have previously tried to sell Maplin in 2011 but pulled out after talks with prospective buyers failed over price.