Workers will leave GKN in Telford on 18 August, Unite said. The end of a Jaguar Land Rover (JLR) contract was behind the loss of 230 jobs.
A further 21 from a hybrid bus project will be "absorbed" by GKN in Birmingham.
The company said it was "the culmination of a process" and it continued to seek new work in Telford.
Unite said it was "disappointed" the firm had not secured more contracts to keep the "highly-skilled workforce in jobs".
The JLR contract, involving 230 welders and engineers, saw workers build chassis platforms for the company's Defender model.
The union's regional officer Matt Jones said he would welcome further discussions about investment and future projects at the Telford site.
"Although these job losses have been on the cards since last December, this is still very bad news for the workers and their families, and, more widely, is a body blow to the Shropshire economy.
"These are skilled jobs that are being lost - the bedrock for UK manufacturing. As a country, we can't afford to lose these skills in a challenging post-Brexit world."
A union says the loss of more than 250 jobs at a car parts firm in Shropshire is a "body blow" to the local economy.