Following a “detailed strategic review” of the plant, ths US-owned company said it expected to end manufacturing by the end of this year.
Bosses said nearly 100 “support-based employees” will continue to work at the base.
A spokesman for Jabil said: “Following a detailed strategic review of the Jabil Livingston site business plan and future loading requirements, we have concluded that there is unsustainable current and future demand to support the viability of the site.
“After careful consideration of all viable options, we are today announcing the commencement of a formal consultation process with our employees, with the intention of a phased run down of manufacturing at the site.
“It is anticipated that manufacturing will cease by the end of calendar year 2017.
“This announcement is set to impact approximately 260 manufacturing employees.
“Our Livingston site will continue to employ nearly 100 global and regional support-based employees.
“Our Ayr plant will not be impacted.
“This announcement is in no way a reflection of the hard work, dedication and loyalty of our Livingston-based employees. We are committed to supporting them throughout the consultation process and subsequent career search.”