The Coronation Street actress, who plays Eva Price on the soap, was posing for a photo with a birthday cake made by celebrity chef Andrew Nutter when the incident occurred.
The candles on the Disney-themed cake got too close to her hair, and quickly set it alight.
Antony Cotton - the actress's Coronation Street co-star - rushed to put out the flames before they spread any further.
Cotton later posted a photo of Tyldesley with the cake, saying: "Birthday update: @Cath_Tyldesley has just set her hair on fire. Actual fire. I put it out but the #privateroom smells of burning bush..."
Tyldesley also thanked her fans for their birthday messages, tweeting: "Can't believe my hair caught fire on my birthday cake! God damn you hairspray!
"Tonight @antonycotton saved my life... Now my hair smells.. Bad..."
Tyldesley recently described herself as "Mr Bean with boobs" due to her general clumsiness.