Harmer has taken 308 first-class wickets in five seasons since arriving in county cricket ahead of the 2017 summer
Simon Harmer has signed a long-term contract extension with Essex, meaning that the prolific off-spinner will remain at Chelmsford until the end of the 2026 season.
The South African joined the county in 2017 and has since become one of the most dangerous overseas players to grace English cricket's domestic circuit in recent years.
Harmer, 32, took 90 wickets for Essex in 2021 across all formats, including two 10-wicket match-hauls in the County Championship.
"The club gave me an opportunity in 2017 for which I will always be grateful," said Harmer.
"Everyone associated with the club have always made me and my family feel welcome since arriving. I'm proud to have committed my future and looking forward to continue making Essex my home for the next five years."
Harmer has taken 308 first-class wickets in five seasons since arriving in county cricket first on a Kolpak deal and then latterly as an overseas player. He also captained the county to the T20 Blast title in 2019.
In May, he claimed career-best innings figures of 9 for 80 in a victory over Derbyshire.
Harmer has taken 308 first-class wickets since joining Essex (Stu Forster/Getty Images)
Essex head coach Anthony McGrath added: "Harmy has been an important part of our success in recent years, and I'm delighted he's committed his long-term future to Essex.
“He's an important leader for us on and off the field and this is a real signal of intent from both him and the club. The talent we have within this team is incredible and his match-winning skills will be instrumental for our plans to achieve further success in the future."
John Stephenson, the county's recently appointed chief executive, said: "Simon is fundamental to our plans moving forward and it's a huge boost for the squad going into the new season."
The securing of Harmer's future follows a swathe of contract renewals, with Aron Nijjar, Paul Walter, Shane Snater, Josh Rymell, Ben Allison and Feroze Khushi all agreeing new deals in recent days.
After uncertainty earlier in the winter, Alastair Cook has also signed a new contract, while allrounder Matt Critchley has joined from Derbyshire, filling the void left by the retirement of Ryan ten Doeschate.