Boohoo has removed co-founder Mahmud Kamani from his chairman role, making him executive vice-chair, and appointed Tim Morris as independent chairman.
The moves come as the fashion retailer's biggest shareholder Frasers stepped up pressure for a more radical management shake-up.
The company, which benefited from a pandemic boom in online shopping, has struggled since then with supply chain problems, higher product returns and competition from rivals. Its first-half core earnings fell by a third.
Boohoo said that Kamani would become executive vice-chair with immediate effect.
Shares in Boohoo were up 2.4% in early trade, while Frasers gained nearly 1%.
Frasers, which holds an about 28% stake in Boohoo, in a statement today called for shareholder meetings to remove Kamani as a director of the company, and appoint Frasers' biggest shareholder Mike Ashley and Mike Lennon as directors.
Frasers has been pushing the fashion retailer to overhaul management and make Ashley CEO. Today's appointment comes nearly three weeks after Boohoo named Dan Finley as its new CEO.
Boohoo said Morris' appointment was part of "a series of decisive steps" taken by its board during its business review, including completing a refinancing, Finley's appointment as CEO, and raising about £39.3m.
Boohoo said its board had decided to create an independent chair to allow Kamani to continue his day-to-day executive role.
Last month, Boohoo announced the departure of then-CEO John Lyttle and unveiled a strategic review that could lead to a potential breakup of the company.
Earlier in November, Frasers called on Boohoo to "publicly confirm" that no assets would be sold without prior approval from shareholders.
