Until November last year, Evans was head of marketing and comms at tech co-location firm DigiPlex, which filed for administration last week.
Since then, he has worked as a freelance PR consultant for tech firms including Tecnikon, Omnijet and RateXchange, some of which are set to move with Evans to the MJ2 client portfolio.
Joll left GCI earlier this year. He completed a three- year earn-out with the agency, which bought Focus Communications - the financial PR agency he co-founded with former GCI Financial chief executive Rupert Ashe.
Current MJ2 clients include Mapeley, Fletcher King, Schroders and Getmapping.
The agency is set to move in July and share an office with PA firm Pall Mall Consult.
Pall Mall Consult CEO Graham Johnson is a non-executive director with MJ2 and Joll said the two agencies are hoping to work together on certain clients and campaigns.