Middlesbrough Council brought the prosecution after its environmental health officers investigated an accident at The Sporting Lodge Hotel in Stainton in November 2016.
Teesside Magistrates' Court was told that the five-year-old tripped over a trailing electric cable to a soup kettle, which contained hot gravy and had been left unattended by hotel staff.
Its contents poured over the child, who required immediate medical attention. Some scars are still visible from the burns.
Here For You Hospitality Middlesbrough pleaded guilty to breaching s 3(1) of the Health and Safety at Work Act. It was fined £6,000 and ordered to pay £1,645 towards the council's costs.
Judith Hedgley, Middlesbrough Council's head of public protection, said: "This company failed to manage their business safety, giving rise to a serious risk to the public which resulted in a child being injured.
"The incident caused significant distress not only to the child but to friends and family at a wedding party which turned a happy occasion into a serious incident."