Oxlade-Chamberlain, 18, was a surprise selection in Roy Hodgson's squad for next month's competition in Poland and Ukraine. Sagna insists Oxlade-Chamberlain, who signed for the Gunners from Southampton last year, can have a dramatic impact on England's campaign.
"Alex Chamberlain came from a smaller team and I didn't know him that well but he has been amazing," Sagna told The Sun. "He plays the game his way and he can be the joker in the pack for England. I'm looking forward to seeing him start some games."
Oxlade-Chamberlain's selection was reminscent of Arsenal team-mate Theo Walcott's inclusion in the 2006 World Cup squad as 17-year-old. Walcott has received criticism for his progress since making his England debut, but Sagna believes the striker is now ready to shine on the international stage.
"Theo and Alex can be the best players in the world because they have such an ability to play football," said Sagna. "They are not scared to play and both started really young.
"Theo Walcott had a lot of pressure on him from a young age. He had a lot of pressure on him when he joined up with the national team for the first time at the age of 17. I know it is not easy to deal with but he did quite well. Of course he had to cope with a lot of criticism but he was younger then and he has a lot of maturity now.
"He was one of our main players this year along with Robin van Persie, scoring goals and creating assists and he can play a big, big part for the English national team this summer."
Meanwhile, Oxlade-Chamberlain had words of support for new manager Roy Hodgson: "The manager is a really good man, he gets on really well with the boys and he has a little laugh but when it comes to doing his job he's been brilliant so far with tactics.
"He lets players like me who like to run at people express ourselves and he gives us the license to do that. So for someone like me who likes to go forward it's exciting to have a manager who lets you do those things. There's a lot of enthusiasm around the camp, everyone is trying to impress because there is a lot of competition for places.
"The first week of training has been hard but really enjoyable and I've learned a lot already. With the new manager coming in it feels like a fresh start - well it would do for me because it's my first trip - but the boys seem like they're really listening.
"He's putting his points across to us, we're taking them on board and putting them into the training sessions."