Wilko plans to close 15 locations in 2022.
Sutton Coldfield, Erdington, Redditch, and Grantham stores are among those to close.
The company, based in North Nottinghamshire, said affected stores will close when leases expire.
Stores in Redditch and Grantham will close in May, while Sutton Coldfield will close in June.
The Wilko store at The Fort in Erdington is also scheduled to close, but no date has been set.
The GMB union said the move may cost hundreds of jobs and was "another nail in the High Street's coffin."
In light of the pending closures, the union has called on local governments and landlords to examine commercial leases and cut rents.
Wilko says the closures will not impact new store openings or retail relocations.
Eleven of the 15 stores have a Wilko within five miles.
Since 1930, Wilko's chief executive Jerome Saint-Marc has been serving customers and communities. "However, the way people buy with us and where they want to shop with us is changing," he said.
"As a company, we're evolving, engaging with landlords for better terms, and looking at locations and store styles."
In order to ensure the future of almost 16,000 team members, we will continue to work together.
"We'll do everything we can to help our affected team members find jobs in neighbouring stores," added Mr Saint-Marc.
"We apologise to the communities affected."
"These closures are catastrophic for Wilko workers and communities," said GMB national officer Roger Jenkins.
This is another blow to the High Street and GMB urges municipalities and land owners to examine commercial leases and cut rents.
In the absence of lower rents, empty high streets and shopping centres are inevitable.
[Wilko] members will now meet with GMB to discuss next measures.
Full list of Wilko stores listed for closure in 2022:
- Edmonton Green
- Merthyr Tydfil
- Narborough Road
- Sutton Coldfield