Witnesses said the family of the 20-year-old bride, Fiza Bibi, had illuminated the entire street and decorated the route of the groom's party with flowers and bunting.
Inkisar Khan, a local police officer, said the fire triggered a stampede and several people were buried when a newly-built wall collapsed.
Khadim said 15 women and six children died at the scene or on their way to hospital and one child and five women died later from their injuries.
Abid Hussain, who lost his son and daughter, said there were more than 100 people in the tent when the fire started and that more than 20 people were still in hospitals in the cities of Dera Ghazi Khan and Multan.
Hospital officials said at least 5 were in critical condition.
The wedding was segregated and the men, including the groom, were in a different tent.
One of the injured women, Fatima, said: "We were sitting on one side talking with each other while some women were singing when there was a fire in the upper part of the tent.
"We ran to save our lives. When we reached the door, some women fell down into the street and then the wall came down."
Residents said that almost every family in the small town had suffered a casualty.
Athar Mubarak, the district police chief, said 4,000 people attended the funeral prayers and that the victims were buried in a local cemetery.