Council chiefs say they have not been able to seal a deal with profits-hit high street clothing giant TK Maxx.
However, M&S are expected to be signed up this week.
The news comes as construction work on the development is due to get under way in the next phase of work.
Councillor Alistair Bradley, leader of Chorley Council, said: “We are currently finalising the legal agreement with M&S with the intension of completing the signing of that agreement this week.
“At this moment in time we have not been able to reach an agreement with TK Maxx and will continue to have discussions with a number of other businesses to fill the remaining units.
“While it is still too early to say who the final occupants will be, we are confident they will improve the offer in the town.”
Malcolm Allen, chairman of Chorley Traders’ Alliance, said: “It might be a disappointment to some shoppers, but no doubt the council has other retailers looking to come to Chorley.
“This is not new. It happened when Market Walk was being built originally – people pulled out at the last minute and people signed at the last minute.”
”The council, which owns and manages Market Walk, has given the go-ahead for construction to begin with a perimeter fence being installed around the side of the Flat Iron that is closest to the by-pass in the next few weeks.
So far, preparation work for the extension has been taking place on one side of the Flat Iron car park with the area in front of Booths completely remodelled to maximise the number of parking spaces available.
Town centre visitors will see a perimeter fence going up around the area closest to the by-pass but drivers will still be able to park there for a short time before the construction work begins.
Diversions will be in place for pedestrians to ensure there is easy access to the existing Market Walk and the rest of the town centre.
Coun Bradley said: “We committed to having roughly half of the Market Walk development signed up before construction could begin and now the work can start.
“It is an exciting time for Chorley as we redevelop the town centre to attract even more visitors and boost the local economy.
“Reel Cinema will bring a six-screen cinema to the town centre and there will be an M&S Foodhall in the development.
“We are determined to make this development a success and will continue to invest in the town centre as that is what people have told us they want to see.”
In recent months there has also been other work taking place with the aim of providing more parking options for drivers.
This includes expanding Hollinshead Street car park, behind the council’s Union Street offices, and turning the spaces on Back Mount and the WhiteHart pub into public long stay parking spaces during the week.
Additionally the council has plans to introduce a free park and ride scheme operating from Morrisons’ car park to Booths every Tuesday and Saturday.
The extension to Market Walk is expected to open in late 2018.
It is part of a £17million plan to redevelop and improve Chorley town centre.