Ahead of their season-opener against Sunderland, the French centre-back spoke glowingly of the striker's abilities, and expects him to match his goal-scoring record at Montpellier this term.
The 25-year-old forward scored 38 goals in 69 appearances during his stint in the south of France, and Koscielny believes that playing with better players will help him to reproduce or even improve on that tally.
"I am happy [he has joined the club] because he played very well at Montpellier," he told the club's official website.
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"I played with him at Tours and he was a great player then - now he is even more confident and scores a lot of goals. I know his qualities and he will give a lot for us.
"I know he has the physical quality to play in this league. For a striker it is [about] confidence and I am sure he is working hard to start well with Arsenal.
"He is tall, like Marounane Chamakh and is also good with his back to goal. I think if we play with technical guys he will be happy, and in the box he is a good finisher."
The two Frenchmen have trod similar paths through the lower leagues of French football before making big-money moves to England -and Koscielny claims he has improved immeasurably since then.
"We have had the same career, and we had some difficulties when we were younger," Koscielny added.
"Now it is better for us and we work a lot - we have found coaches who gave us confidence."