Welbeck struck a hat-trick - his first competitive one - as the north London club thrashed their Super Lig opponents 4-1 in the UEFA Champions League.
England international Welbeck only cost manager Arsene Wenger a reported £16million to sign from Manchester United, and it is turning out to be an inspired buy.
Midfielder Oxlade-Chamberlain said he was aware of Welbeck's quality before his arrival in London.
"It's nice to see 'Welbs' do so well tonight," Oxlade-Chamberlain is quoted as saying on UEFA's official website.
"Danny is a great player and he has shown it for many years at Manchester United.
"I knew when he came to this club, the way we like to play football and try and find through balls, with his pace and his intelligent runs, we'll find a lot of him.
"The boys did that tonight and I was glad to help assist him for his last goal.
"Tonight was all about him, he did really well for us on and off the ball. I try and create goals so I am happy I was able to help him."
Defender Chambers also joined Arsenal earlier this year and said his fellow arrival has taken no time at all to feel at home at the club.
"He's an athlete - he's got pace, power, he's great on the ball," Chambers told Arsenal's website.
"He's willing to work hard and you can see that he's a goalscorer.
"He's everything that you can ask for really. He works hard and he's a great influence [on the team].
"[Danny] has settled in really well. When I first came, I said that the bunch of lads and the staff here were so welcoming. It's hard not to really settle in quickly."