The retailer, reporting on the three months ending 31 March, said that food sales were up 0.1% year on year and 2.5% compared to Q4 of 2013.
Discussing the termination of its website partnership with Amazon, M&S said that it had cut its "usual level of marketing activity to ensure a smooth transition", adding that in May it will launch a marketing campaign to promote the new site.
In spite of the upheaval of its website migration, the retailer reported a 12.5 % year-on-year hike in online sales.
News of M&S’ 0.6% fall in non-food sales was met with a degree of optimism by the City, which was expecting a more dramatic decline.
Marc Bolland, the M&S chief executive, said: "We delivered another quarter of improvement in general merchandise. Clothing sales were up 1.3% in total, up 0.6% on a like-for-like basis. We are encouraged by womenswear, which is showing clear signs of improvement and performed ahead of clothing.
"Our food business had another great quarter, especially considering the later timing of Easter. This marks our 18th consecutive quarter of growth. We continued to outperform the market with record sales around key events including Valentine’s Day and Mother’s Day."