Trading standards officers had furniture found at Hornsea Garden Centre failed flammability tests by independent inspectors.
The company admitted it did not have procedures in place to check the labelling of products before the items were put on sale.
The firm was prosecuted alongside two of its suppliers, Coventry-based Mosley Trading, and Orchid Designs from Huddersfield.
Mosley Trading Company was fined a total of £2,000 for each of eight offences committed, and told to pay costs of £3,615.54.
Orchid Design Ltd was fined £1,250 for each of two offences committed and told to pay costs of £3,325.76.
Colin Briggs, trading standards manager at East Riding Council, said: "These chairs and cushions were very dangerous and posed a serious fire risk to those who had bought them.
"The companies involved in this case were all experienced traders who failed in their obligations in relation to the safety regulations when simple physical checks would have revealed the inadequate labelling of the products.
"I would urge anyone buying items such as cushions and soft furnishings to ensure they have the correct safety labels attached so they know the items they are taking into their homes are safe."
It is unclear whether the products involved were indoor or outdoor furniture.