Essex director of cricket Chris Silverwood told the club website, external: “He is a proven international performer and one of the most complete all-rounders in the game today.
“His ability to contribute consistently with both bat and ball will add real balance to our squad, and his experience at the highest level will be invaluable to our group.”
Mulder, who also played for Kent and Leicestershire, will be available for the Championship opener against Hampshire at the Ageas Bowl on 3 April and will play his final game in the T20 Blast at Chelmsford on 9 June.
“I am really excited about joining Essex and coming back to the UK for a new challenge,” he said.
“I have always had great experiences playing here and am looking forward to seeing what we can achieve together.”
Mulder will join fellow South Africans Simon Harmer and Dean Elgar at Chelmsford – although the latter does not count as an overseas player as he also has a UK passport.
