The furniture company, which bought Churchill Square Shopping Centre in Brighton last year, is set to open in the former Debenhams unit on the upper two levels.
It has now been revealed the store is expected to open in 2025.
The announcement came as Ikea UK revealed a slump in sales for the past year as under-pressure shoppers held off buying bigger-ticket items.
The UK arm of the Swedish homeware giant said the fall was also partly driven by price reductions to keep attracting customers hit hard by the higher cost of living.
The company revealed that retail sales dropped by 6.8 per cent to £2.3 billion for the year to August, compared with the previous financial year.
Read more: New Ikea click and collect service is approved and will open
Ikea linked the drop to a “strategic decision to prioritise affordability” as it invested more than £117 million into lowering prices over the year.
Peter Jelkeby, chief executive and chief sustainability officer of Ikea UK, said: “In a year of economic uncertainty, our priority was clear: stand with our customers.
“In spite of our reduced turnover, continuing to lower prices remains our long-term priority.”
The retailer, which is owned by parent group Ingka, said more than 3,000 products, representing about a third of its range, were reduced in price.
It said there was an “uptick” in demand as the year progressed, supported by more price reductions, which helped improve sales in categories such as kitchens, bedrooms and storage.
Ikea UK said it is also continuing to make progress on its expansion programme, with the upcoming 2025 openings of two new city centre stores, one in Oxford Street in London, and the one in Brighton.
Mr Jelkeby added: “We continue to dedicate our energy to our UK expansion plans and investing heavily to become more accessible.
“To complement our existing stores, we are laser-focused on continuing to innovate to reach more customers, with a network of new, smaller stores that offer different experiences, as well as new services that meet all of our customers’ needs – no matter where they live.”
On Thursday, Ingka revealed that the global Ikea group saw retail sales drop by five per cent to 39.6 billion euros (£33.2 billion) for the year.