The Bournemouth-based company, which publishes magazines like How It Works and X360, is headed by ex-Paragon Publishing editorial director Damian Butt.
Butt founded the company along with former 3i man Steven Boyd and former Paragon designer Mark Kendrick in 2005.
The Truells, who invested in the company to get it up and running eight years ago, said the additional investment was growth capital to help push the firm to grow internationally.
Edi Truell said: “The team is now ideally positioned to lead and transform the migration of published content to digital platforms worldwide.”
The investment has been made separately from the brothers’ current ventures. Edi is currently chair of Disruptive Capital, with Danny chief investment officer of the Wellcome Trust.