The blaze broke out at Peggy's Place, in Blakenall, at around 3am.
A charred van stands in the middle of the courtyard and singed wood is strewn among charred debris after firefighters spent hours bringing the blaze under control.
Bosses at the furniture shop today said they believed the fire could have been started deliberately.
It began in the workshop area and courtyard at the rear of the shop, in Barracks Lane, Blakenall, and spread to an area of the courtyard where furniture was being stored for delivery.
Firefighters from Bloxwich and Fallings Park attended after neighbours raised the alarm.
Co-owner Matthew Cooper, aged 33, of Highgate in Walsall, said: "We believe it started in the workshop where we build furniture.
"It spread to a van which we use for deliveries and an area where we keep the furniture.
"We've lost around £10,000 to £15,000 worth of stock.
"We are gutted."
Mr Cooper said the yard had been targeted by vandals and thieves a few times in the past, with tools stolen.
Investigators will comb the scene for clues in a bid to establish whether arsonists were responsible for the blaze.
Fire crews today declined to comment on the cause until specialist investigators arrived.
They left the scene after more than four hours just after 7.30am today.
Police were due to attend the scene later today.