A couple, aged around 50, and their 13-year-old daughter fled their house at Hillcrest Drive in Castleford after the fire broke out in the early hours of the morning.
Knowing his family were safe, the man then went back inside to try and put it out.
Watch Commander David Smith of Castleford Fire Station said crews were called at around 4.45am.
He said: "Everyone was in bed and it appears that a toaster on the worktop in the kitchen had caught fire. We are still investigating why.
"We want to warn people to make sure that appliances that can be turned off are done so when they go to bed."
A smoke alarm alerted the family to the blaze and they escaped unharmed.
Watch Commander Smith said the kitchen was full of "thick smoke" from the burning plastic and has been left fire damaged.
He said: "The man had gone back inside and tackled the fire with an extinguisher.
"He had done a great job but we don't advise that really.
"The main thing is they all got out safely."