The coach believes the midfielder, who has "seen everything in football," will bring a lot to his Bayern side and says the transfer desire was a mutual one.
The 32-year-old ended his five-year spell with Real Madrid to join up with the former Barcelona coach at the Allianz Arena in a deal worth an estimated €10 million.
Guardiola believes that the two-time Champions League winner will add even more experience to his Bundesliga-winning Bavarians and is always pleased to sign players who think with their head before using their feet.
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"Alonso is very experienced," the Bayern coach told reporters. "He has seen everything. He is a model professional and will help us. He is a great catch. I am very pleased that he is here. He is a very intelligent player and we need intelligent players.
"Xabi wanted to come here and we wanted him to come here. It is not necessarily just the quality of Alonso which is appealing - he has achieved everything."
Bayern travels to Schalke on Saturday looking to notch its second successive Bundesliga triumph of the season following last weekend's 2-1 home win over Wolfsburg.
"We know how important this game is," he added. "Schalke's always hard to play at. We need a good performance."