The France international striker squandered Arsenal's best chances in their 0-0 draw against Everton on Tuesday but has impressed during his debut season in England, scoring 17 goals in all competitions.
Giroud was praised by Arsène Wenger ahead of this weekend's London derby and Koscielny has also been impressed by his compatriot.
"I think for his first season in England he's played well," the defender told Arsenal Player. "He scored a lot of goals.
"The first year is the most difficult [for foreign players] because we don't know English football. I think he's adapted very well in this country and he will be better and better for next season.
"He's OK [after the Everton game]," added Koscielny. "He's a professional. He had some opportunities to score for the team but I think he will be ready [to score on] Saturday against Fulham."Copyright 2015 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