The Chile international impressed against Manchester City at Wembley on Sunday, causing the champions considerable problems with his pace and direct running on the counter-attack.
Alexis can operate on either flank or through the middle and Giroud believes he will help Arsenal challenge for honours this season.
"I've played with him in training," Giroud said. "We have a good understanding - like Mesut [Ozil] when he signed for Arsenal. It's always easy to play with these kind of players. I think he will maybe need some more games to adapt his game to the Premier League but that's normal and he's a fantastic player so I think he will [have] a great season.
"He has different qualities to me, Yaya Sanogo and Joel Campbell. He can bring his pace and his technique in the centre of the park and he's a great finisher. We have a good quality squad and now the quantity too, so that's why I think we will be stronger this year.
"Last year we did well until March. We had a bad run after but we really wanted to come back and be stronger than last year. I think when our Germans join us, we will be stronger for sure and hopefully [we can compete] until May."Copyright 2017 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source