Marks & Spencer's online business M&S Direct saw sales rise 49% in the first quarter of the new financial year.
Overall UK sales were up 4.4%, with the online side of the business playing a strong role in the performance.
The company has invested in its online business in recent months. It extended its Shop Your Way multi-channel ordering service to more than 400 stores and has launched a fully mobile-enabled website.
Chief executive Mark Bolland said in his interim management statement, "Marks & Spencer has delivered another good sales performance in the first quarter, continuing the progress made by the team over the previous year. We have continued to grow market share across all parts of the business as customers recognised the strength of the Marks & Spencer brand and the great quality and value it represents."
But despite the strong performance the company reported a cautious outlook ahead of the rise in VAT, which it fears could affect consumer confidence.