The 20-year-old has been on trial at the Hive for the last few weeks and obviously impressed Bees manager John Still – who had his say on the player after his side’s narrow defeat to Ipswich on Saturday.
"For his first start at the club, Josh was absolutely exceptional,” he told the club’s official website. “He was quick, he was strong and he was brave.
“He wasn't afraid to take people on and he showed his pace. I was absolutely delighted with him and I'm really happy to have him here."
Starting at Tottenham academy before moving to Fulham - the forward was on the books of Hendon last season, scoring 17 times in 42 appearances.
Walker made no bones about his goals and expectations for the coming season – telling the club’s official website that he isn’t here to simply make up the numbers.
"Last year at Hendon I did quite well, now I'm here and I want to push on and show everyone what I'm capable of going to the next level.
"There's a step up but I think I'm ready and hopefully we can get back into the League."