The 33-year-old, who was club captain from 2017 to 2021, has taken 456 first-class wickets for the county and has finished as leading wicket-taker for six seasons.
Leach, who was born in Stafford, has been struggling with a knee injury so far this summer, but wants to end his Worcestershire career on a high by staying in division one of the County Championship.
He said: “Like all these things, there are a lot of factors that come into it. I’ve heard that cliché a lot ‘when you are ready, you know you are ready’ and that has kind of dawned on me this season.
“The knee injury, although not the sole contributory factor, has certainly played a part in my decision. The body is probably not able to do what it once was.
“But outside of that, I’m just ready really. There is a multitude of reasons that feed into it and I just know – and that is the only thing I can say, I guess.
“I think there comes a time in your career when you are excited for the next chapter and that’s where I’m at now at this moment.”
“I’ve achieved more than I ever thought I would do in the game but there is one little frontier, one little barrier that I’m massively keen to achieve before I sign off at the end of September.
“That is for us to retain our status in Division One and to help the guys in August and September to do that.
“I’m back bowling with the plan to be, all things being equal to be ready for that Kent game in August.
“I’m desperate to make sure I’m back and ready and putting myself and the team in the best possible position to achieve what we want to at the end of the year.
“If we can stay up, it will be a great achievement. I reckon it will be the best thing we’ve done in four-day cricket since I’ve been
here.”
Leach is currently doing a coaching role while the Metro Bank One Day Cup takes place but is hoping to add to his 456 first-class wickets when he returns later in
August.