The pair were caught on camera dumping the waste in the B&M car park in Carlisle Street, near the bus station, yesterday morning (Wednesday, October 13).
In the video, two men in hi-viz bibs and safety helmets can be seen flinging rubbish from the boot of a black Ford car into a hedge.
The dumped rubbish reportedly included cardboard boxes, plastic bags of waste, children's clothing and a used nappy.
The men allegedly wore hi-viz bids with the name of a North West property developer on the back. The company has been approached for comment.
Councillor Robert Boswell, cabinet member for environment at Preston City Council, said: "Littering and fly-tipping is awful behaviour that causes blights on our streets and takes up a great amount of time and resource for the Council, which could be better spent elsewhere.
"We ask that everyone disposes of their waste and recycling in a responsible manner using the bins provided, in order to keeps the streets of Preston free of litter and fly-tipping.
"It is important that people report any fly-tipping incidents via our website immediately, giving the team all the details they can including specific locations, so they can be actioned appropriately as soon as possible."