The company employs 780 workers in total, another 50 out of 63 jobs may also be at risk at its Uttoxeter and Wakefield distribution centres.
A consultation period, due to last "a minimum of 45 days", has begun as the proposals are considered and work is done to "reconfigure" the sites, the company said.
In a statement, 2 Sisters said to "maximise new growth" it has had to make "tough decisions".
"Regrettably, our loss-making site in Uttoxeter requires urgent attention and biscuit production lines need re-configuring. Around 250 roles will be at risk of redundancy,” it said.
"Additionally, a smaller number of colleagues, around 50, at our Uttoxeter and Wakefield distribution centres will also enter into consultation as we explore proposals to out-source this warehousing work."
Unite regional officer Rick Coyle, regional officer, Unite trade union said the news that the management at Fox’s Biscuits is planning to reduce the 700-strong workforce at the Uttoxeter site in East Staffordshire by up to 240 jobs by August this year is a massive blow to the workforce, their families and the regional economy.
“Nationally, we are pressing for an urgent meeting with the parent company, 2 Sisters Food Group,” said Coyle.
“We are having our first meeting with the shop stewards and management on Friday (22 March) where we will digest the full implications of this announcement.
“Unite will be giving maximum support to our hundreds of members at Uttoxeter in the days and weeks ahead at what is a difficult time for the workforce.”
Fox's Biscuits was established in 1853 and employs 2,000 people across three sites, in Staffordshire, West Yorkshire and Lancashire.
Workers at the Staffordshire factory have been left fearful about their futures after being told 250 roles are under threat.
An estimated 1,000 tonnes of biscuits are made at the Cheadle Road factory each year and it is a major employer in East Staffordshire.
A spokesman for Fox's Biscuits added: "Fox's Biscuits has recently committed to a major investment plan to maximise new growth and commercial opportunities.
"As part of this plan we have informed colleagues there are number of tough decisions to make as we review manufacturing capabilities to give us the best possible chance of sustained success.
"Regrettably, our loss-making site in Uttoxeter requires urgent attention and biscuit production lines need re-configuring to ensure it has a longer-term, viable future.
"This means we will be entering into consultation with our colleagues around proposals to restructure the site. Circa 250 roles will be at risk of redundancy."