The Ritrama Group is the largest privately-owned self-adhesive company in Europe. Its UK site is based in Greater Manchester.
Amicus took its case to the CAC after the firm refused to negotiate a voluntary recognition agreement with the union, which claimed it had more than 50% of the workforce as members.
The CAC ruled that the company must recognise Amicus to represent its members for collective bargaining following a membership check which confirmed the numbers.
The company now has 30 days in which to conclude a formal recognition agreement with the union.
Tony Burke, Amicus assistant general secretary, said: “We are pleased with the CAC decision and I want thank our members at Ritrama who have waited three years get union rights.
“We hope that the company will now listen to its workforce and sit down with us to work towards building a relationship which will benefit the company and its employees.”