Don't worry, it's not a Tottenham shirt, just a very big England one.
It's a Thursday, which means plenty of Premier League footballers are posting photos and videos of themselves as youngsters for the weekly throwback Thursday ritual on Twitter.
He posted this photo on his Instagram earlier today, which shows him in his first ever football kit.
Like he says, it looks like his parents wanted him to grow into the kit which looked slightly too big for him.
Of course his dad would have been dreaming of him one day playing for England, as he did. His old man is former Stoke City and Portsmouth winger Mark Chamberlain, who played eight times for England in the 1980's.
The kit is certainly an age away from the body-hugging Puma kit he sports for Arsenal these days.
Oxlade-Chamberlain has had a good season for Arsenal this term. He has played in 39 matches this term and scored four goals, including a stunning strike against Monaco and a goal for England against Scotland.
He will now be hoping to tie off the campaign with a top four spot and potential FA Cup winners medal.