Xhaka, who put in an impressive performance in Switzerland's 1-0 win over Albania at Euro2016 on Saturday, will be plying his trade for the Gunners next season following a £30million-plus move from Borussia Monchengladbach.
Hamburg defender Djourou, who was with Arsenal between 2003 and 2014, said of Xhaka: "He's a top-class player with lots of qualities.
"I think he'll do Arsenal a lot of good. There's huge competition - but I am sure that he has the quality to impose himself.
"He brings calmness, his ability to play long passes, precision and aggression."