Womenswear sales at John Lewis grew 34.5% last week compared with the same week in 2016, as overall fashion sales jumped 15.5%.
The retailer said its own-label denim lifestyle brand, And/Or, performed particularly strongly for the week to 22 July.
Beauty, wellbeing and leisure sales enjoyed an increase of 13.4%.
Total sales for the week grew by 8.9% to £79.8m. John Lewis said it was one of the best-performing weeks for online traffic so far this year.