Yobo, 31, had been at Fenerbahce for the past two seasons and finally made the move permanent after both clubs agreed to an undisclosed transfer fee.
"The permanent switch is done and I am also switching to help the team do well on the pitch," Yobo told Everton's official website.
"It's been a long journey into achieving this dream and now is the time to pay the club and fans back with a great performance."
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