Cowan awarded benefit in 2006
Cowan, 30, who toured the Caribbean with England but failed to make an international appearance, made his debut for Essex in 1995 but his career has been blighted by injury.
"I have received a lot of support from the Club and it is an honour to have been given a benefit," Cowan said. "It's been a frustrating period over the last three or four years with my knee injury resulting in such a long time out, coming back and getting a little bit involved last season but then this year has not been as successful as I hoped it could have been. But the club have stuck by me over the last few years and have awarded me a benefit."
David East, the county's chief executive, added: "It is always a great milestone for any county cricketer and we are particularly pleased for Ashley because he has been troubled by some career-threatening injuries. We wish him well for next season and hopefully he will have a very good benefit to reward him for the service he has given us."
In 102 matches for Essex, Cowan has taken 280 wickets at 32.26 and scored 2231 runs at 17.84.