Barcham, 22, penned a new two-year deal this week after a successful campaign last time out following his arrival - initially on loan - from Tottenham in September.
He scored nine goals last season and was runner-up at the club's player of the year awards, as well as becoming a huge fans' favourite.
He said: "I'm really happy to be at Gillingham. As soon as I arrived at the club I settled in quickly and was playing some good football.
"The gaffer (Mark Stimson) is able to get the best out of me and when you find the right fit, you don't want to leave.
"I get on well with the lads and the coaching staff and the fans have been great. Football-wise, we like to attack and that suits my style as I'm a player who likes to get at the opposition defence."