Boohoo shares have taken a beating in recent days.
They've lost about a third of their value since the weekend.
That after a Sunday Times report alleging workers at one UK factory endured dire conditions, and were paid just £3.50 per hour - about $4.40.
Its clothes have been dropped by Amazon and other third-party retailers as a result.
Campaign group Labour Behind the Label also said it had reports of workers forced to come in while sick with Covid-19, and factories operating illegally through lockdown.
Now the online fashion brand says it will review conditions at all suppliers.
The probe will be lead by an independent lawyer.
Boohoo has been growing fast, and also owns brands including Pretty Little Thing and Nasty Gal.
Before the reports it was valued at 5 billion pounds - about 6.2 billion dollars.
That's twice the value of Marks & Spencer, Britain's biggest clothing retailer by sales value.
But shares in Boohoo were down another 12 percent on Wednesday (July 8) morning alone.
