Wedar will replace Stefan Gustafsson, who was named acting chief executive of the business in December 2016.
Wedar, who previously held several senior management roles within the digital industry, joins from Eniro.
Speaking of the appointment, Per Norman, chief executive of Mr Green & Co AB, said, “We are very happy that Mattias joins Mr Green he has a solid background in the digital industry and a thorough experience from technology development as well as marketing and products.
“Mattias will be key in our further implementation of the business strategy Mr Green 2.0 and the continuous development of our technology platform which we launched last year.
“Our strategy encompasses a clear plan to develop an even stronger customer experience, based on digital technology and our customers’ individual preferences.”