Crawley have also signed 22-year old striker Bloomfield from newly-promoted Premier League side Norwich City on a season-long loan.
Director of Football Selim Gaygusuz said: “We are delighted to have Mason at the club. He is a player we have kept an eye on for a while and it's a shame that last season was cut short because of injury.
"He's tall, athletic and has an eye for goal and he will give us something different in terms of our options up front. He is a very good prospect and someone who we believe can make a big impact with us."