Patel oversaw a period of reform that resulted in international cricket returning to Headingley and a focus on improving equality, diversity and inclusion but also saw the departure of a significant number of staff.
"It has been an honour and a privilege to work for such a prestigious organisation," he said in a club statement.
"I have made the difficult decision to step aside at the next AGM and enable the club to continue on its important journey of change under a new chair.
"I would like to thank those members who have been hugely supportive of the changes that the board have introduced at Headingley. I would also like to thank the staff and board members who have all worked tirelessly during what has been a transformational period in Yorkshire's history.
"There is still much for the club to do, but I have the strongest faith that Yorkshire will be back at the pinnacle of English cricket for the long term."
The departures of high-profile staff members, including the entire coaching team, proved highly controversial and Yorkshire agreed costly settlement packages after accepting the dismissals were procedurally unfair.
Patel said he has no regrets, though, telling The Cricketer: "It was absolutely the right thing to do. By instinct, I always want to take people with me on the journey. But some people wouldn't accept the extent of the problem or the need to change. We had to move on without them.
"It wasn't just about Azeem, either. I spoke to hundreds of people who had suffered in a similar way. But they won't come forward as they have seen what happened to Azeem.
"And it wasn't all institutional racism. There was some very deliberate, very conscious racism."
Patel has faced strong criticism for his role in the events of the last year, and he said: "My hope is that, when I go, I will take the criticism with me and the new management at the club will be able to move forward without any of that baggage.
"We had a small group of people who wanted to find procedural obstacles to thwart our progress, and we have had to spend many hours and much money to counter them.
"Ironically, I would have left the club much quicker - which seems to be what they want - had they not tried so hard to derail me."
Rafiq tweeted his praise for Patel, saying: "So much to say on this but for now - Lord Kamlesh Patel should be thanked for making sure @YorkshireCCC (has) still got the lights on."
Stephen Vaughan was appointed chief executive at Yorkshire in November while Darren Gough took on the role of managing director on a permanent basis.
Vaughan said: "Kamlesh should be extremely proud of what he has achieved at Headingley during his tenure as chair. The structures that have been put in place are vital in ensuring that Yorkshire is a club that people are proud to be associated with."