"We thank Michael Williamson for his two years at Wrexham and for his work taking the club from League One to the Championship," co-chairmen Rob Mac and Ryan Reynolds said in a joint statement.
American Williamson joined Wrexham in the summer of 2024.
Before moving to Wrexham, Williamson held senior positions at Inter Milan and in Major League Soccer. He was named Football Industry Leader of the Year in 2025.
Harvey, who has extensive experience in English football administration and has served on Wrexham's board, will assume the CEO's duties.
Wrexham narrowly missed out on the Championship playoffs last season and have made an inconsistent start to the new campaign. They are currently 16th in the table.