Ajax signed former Germany international Heiko Westermann from Real Betis to a two-year deal on Saturday.
The centre-back moves to the Dutch giants on a free transfer despite having a year left on his contract in Spain.
"I am very happy with my contract at Ajax," the 32-year-old told the club's official website.
"We had a great chat last week and I immediately knew that I wanted to join Ajax. It's fantastic that it's all gone this quick.
"Ajax are a great club with a world-famous philosophy....