Kehrer, 29, joins from Monaco. Ajax have not negotiated a buy option in the loan deal.
The Amsterdam side had been looking for a right-footed centre-back after the departures of Ko Itakura (Borussia Monchengladbach) and Josip Sutalo (Lazio, loan). A surprise signing of Thilo Kehrer was first reported on Tuesday, one day before the Dutch transfer deadline.
"Thilo is an extremely professional and accomplished player who brings a wealth of experience," technical director Jordi Cruyff said after signing the 28-time German international.
"He possesses a strong mentality and is accustomed to performing under pressure at the highest level. His presence will also create healthy competition in defence, which is essential for maintaining balance and intensity within the squad."
'He didn't have to convince me'
In his opening interview with the club, Kehrer explained what Cruyff said that brought him to Amsterdam.
"He didn't have to convince me much. He explained to me what the plan is, what the expectations and ambitions are, what the team is like, how the coaches work with the team... It all sounded very positive to me. It gave me a good impression of what to expect and what is expected of me."
Kehrer already has a rich footballing career behind him, having played for Schalke 04, Paris Saint-Germain, West Ham, and Monaco. Last season, Kehrer played 40 games for Monaco in Ligue 1, the French Cup, and the UEFA Champions League.
Kehrer joins Ajax on the back of their joint-worst points finish in over 60 years and is the latest piece in Cruyff's attempt to restructure the squad, with the German defender Ajax's tenth signing of the summer. Kehrer is the third German to join Ajax this summer after Marc ter Stegen and Julian Brandt.
"I spoke to Marc in the last few days about how he feels; he asked me if there was a possibility for me to join. We had good conversations about Ajax and how he likes it here. That was another confirmation for me. It's nice to reunite with old teammates: him, Julian, Caio (Henrique), who I played with at Monaco."
Kehrer's first test as an Ajax player will be against reigning champions PSV, who visit Amsterdam on Saturday, September 5th.
"I'm ready to play. I did the whole preseason with Monaco; I feel fit and in shape. I'm ready to get started."
Ajax are not expected to be done in the transfer market, with Sunderland winger Simon Adingra set to join on a season-long loan deal as well.
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