The Business Growth Fund (BGF), set up by the UK's five big banks, invests up to £10m in firms.
Decora will use the investment to expand into European markets.
BGF's other investments in Northern Ireland include the kitchen manufacturer UForm and the Bob & Berts coffee chain.
Decora employs more than 1,000 people at its headquarters in Lisburn, with further facilities in Birmingham.
In 2018, it turned over £73m and made a pre-tax profit of £4m.
Decora chief executive Stuart Dickson said all businesses have faced an "incredibly turbulent" few months but his firm was fortunate to have "a very robust and strong underlying business, and a brilliant and resilient team".
Decora has recently completed the acquisition of Domus Lumina, a €10m (£8.7m) turnover Lithuanian-headquartered manufacturing partner.
Mr Dickson said they were continuing to explore other potential takeover targets which they had identified pre-Covid.
"BGF has delivered on a partnership agreed before the onset of Covid which will put the business in a strong position to continue our growth strategy as the world adapts to the new normal," he said.
BGF's David Gammie said Covid-19 had created uncertainty for all businesses in Northern Ireland.
"Decora has taken responsible and all necessary steps to safeguard its team during this period, and we look forward to working with the management team to support the longer-term growth plans of the business."