Melanie Smith, chief executive of the joint venture between Ocado and Marks and Spencer and a key figure in its creation, will leave the business at the end of August.
Smith, who was previously a strategy director at Marks and Spencer but has run Ocado Retail since its formation in 2019, will be replaced by non-executive Lawrence Hene on an interim basis.
She said on Tuesday that it was “the right time to move on to new challenges”.
Tim Steiner, the Ocado co-founder who chairs the venture, praised Smith’s “incredible energy”, adding that there was “no question that [she] leaves the business well prepared for faster growth in the years to come”.
A permanent successor will be appointed “in due course”. Hene was previously deputy chief executive of the business when it was still part of Ocado Group.
Sales at Ocado Retail boomed during the pandemic, although it was held back by the difficulty of rapidly expanding its centralised fulfilment centres compared with what supermarkets were able to do.
In recent months, sales growth has slowed as shoppers have returned to in-store rather than online shopping and average basket sizes have shrunk from their pandemic highs.
In its most recent trading update, Ocado Retail said sales growth in 2022 would be in mid single digits rather than the 10 per cent previously forecast.
Data from Kantar published on Tuesday showed that Ocado Group sales were up 0.7 per cent year on year in the most recent 12-week period, maintaining its overall UK market share of 1.8 per cent.
One person briefed on Smith’s departure said it was “categorically not related to current trading” but another person who knows her well acknowledged that the challenges facing Ocado had mounted over the past year.
“It is going to be hard yards . . . and Mel is very much a start-up kind of person,” the person said.
Smith created the organisational infrastructure that Ocado Retail needed to function independently from Ocado Group and managed the transition from Waitrose own-brand products to Marks and Spencer lines.
Ocado Group shares closed down 3.2 per cent at 755p on Tuesday, a long way from their 2020 highs of over £28. M&S shares were up 4 per cent.
Ocado Retail is due to report half-year results on Thursday.