The Morocco international has all but confirmed he will leave Bordeaux for Emirates Stadium on a free transfer in the summer.
Boss Arsene Wenger hopes that Chamakh will add a predatory instinct to a side who only just missed out on the Premier League title.
And Sagna does not doubt that the 26-year-old will benefit Arsenal after facing the forward during his days with Auxerre.
The full-back said in the Daily Mirror: "I know him. I played against him. He is top class.
"He is very good in the air and he scores a lot of goals from crosses. He keeps the ball very well and it will only benefit us to have a player like him in the team."
Sagna has also urged Arsenal fans to keep faith in boss Arsene Wenger after another trophyless season.
He said: "As a team we can always be better and we be will next year. But it's not always about money. Money is not everything."
Sagna added: "As a player of course it hurts to hear the criticism because when you are close to winning something and you don't it's a real disappointment.
"Slowly but surely we are learning how to win ugly. We know there have been many games this season where we have led, yet conceded easy goals.
"But we will learn from that and we continue to trust in the manager.
"I can understand how the fans feel because as a fan you always win to win something. Everyone understands them. But I can only tell them that we are very close."
Sagna has also backed Sol Campbell to earn a place in England's World Cup squad following the veteran centre-back's excellent end to the season after joining the Gunners in the wake of his Notts County exile.
He said: "Sol has been brilliant this season. I'm surprised because he nearly stopped football and he didn't play for six months.
"Its always very difficult to come back. But in many games he did very well even though he is 35 years old and I wouldn't be surprised to see him involved with the national team at the World Cup."