Republic co-founder Carl Brewins has stepped back from day-to-day involvement in the business after 26 years.
He will remain a non-executive director of the branded young fashion retailer, citing personal reasons for the change.
Brewins launched Republic with chief executive Tim Whitworth in 1986, and along with chairman Andy Bond and private equity backer TPG, invested a total of £20m in the business before Christmas.
TPG took a 60% stake in Republic in a £300m deal in 2010 from former owner Change Capital, the private equity house headed by former Marks & Spencer boss Roger Holmes.
Last summer, Republic asked its banks for greater financial headroom, although it had not breached its covenants.
Republic was understood to be keen to take advantage of good property deals while improving IT systems and adding more brands. It has ambitions to double its 200 stores.
No one from Republic or TPG was available for comment.