Baroness Tanni Grey-Thompson has become the fourth member of the London 2017 Athletics World Championships board to resign in the last six weeks.
Grey-Thompson announced her decision at a Sport Industry Breakfast Club event in London on Thursday.
The 11-time Paralympic champion said her role had become "a bit too tokenistic" as London prepares to host the International Paralympic Committee Athletics World Championships alongside the IAAF event.
Next year the capital will host the World Athletics Championships after being awarded hosting rights for the Olympic Stadium in 2011.
Sally Bolton last month quit her post as managing director of London 2017 for "personal reasons", a week after Martin Stewart and Heather Hancock stepped down from the board.
A statement from London 2017 read: "London 2017 can confirm that Baroness Tanni Grey-Thompson has stepped down from her role on the board of 2017.
"She has taken the decision in order to dedicate her full attention to her work in the House of Lords, and her new responsibilities leading the development of a Duty of Care for Sport and the protection of those most vulnerable in society."
Ed Warner, joint chair of London 2017, added: "London 2017 would like to express our sincerest thanks to Baroness Grey-Thompson who has supported the work of the championships through these early milestones through her role on the board.
"London 2017 will be the first time that the IPC and IAAF World Championships are staged in the same city in the same year, and her vision for inclusivity has been key to bringing that to life."