The UK Government and the drugs firm are investing in the Livingston plant, with 75 new jobs expected to be created.
The Government had struck a deal for early access to Valneva's "promising" vaccine candidate.
If clinical trials are successful, the site could provide up to 100 million doses of the vaccine across the UK and internationally.
Business Secretary Alok Sharma will visit the factory this afternoon to hear about plans to scale-up production.
Valneva's vaccine, which is called VLA2001, is one of four potential vaccines which the UK Government has secured rights for.
Mr Sharma said: "I'm incredibly grateful to our highly-skilled scientists and technicians in Livingston who are supporting the global effort to research, develop and manufacture a safe and effective coronavirus vaccine.
"The multimillion-pound upfront investment we have agreed with Valneva today means that their vaccine can be manufactured in quantity right here in Scotland.
"If clinical trials are successful, millions of people in priority groups across the UK will be protected by their life-saving vaccine."
Speaking on the BBC's Good Morning Scotland radio programme ahead of his visit, Mr Sharma said the French company hoped to secure regulatory approval for its vaccine in the second half of next year.
Mr Sharma said: "We're looking at a whole range of ways we can support and bring forward a successful vaccine, in addition to that we're also investing in manufacturing in the UK and supporting the international effort."
Scottish Secretary Alister Jack said: "We are doing everything possible to keep people in all parts of the UK safe as we tackle the coronavirus pandemic.
"The UK Government is purchasing millions of doses of coronavirus vaccine for distribution across all parts of the UK.
"A safe and effective vaccine is vital to the long-term protection against the virus we need.
"I'm particularly pleased that Scotland's world-class research sector is playing such an important role in developing a much-needed vaccine."
Valneva said the final supply agreement would be concluded in the coming weeks.
Chief financial officer David Lawrence said: "We are delighted to receive initial funding from UK Government to support the expansion of our Covid-19 vaccine manufacturing facilities.
"We are thrilled that the Secretary of State has made the time to travel to Livingston and to visit our site, it's a real sign of the Government's commitment."
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