Author JM Barrie credited the gardens of the town's Moat Brae house as his inspiration for the work.
Ms Lumley unveiled a wood-carving of his most famous creation at the entrance to the town.
She is already a patron of the appeal launched last week to turn Moat Brae into a children's literature centre.
The Peter Pan statue was provided by the action group, the People's Project, which is working to improve the appearance and reputation of Dumfries.
Ms Lumley said she was amazed at the work which had gone into the wood-carving.
"I absolutely love it - I am so impressed that it is all made out of one enormous spruce tree trunk," she said.
"It is absolutely enchanting and it is standing outside the garden centre so everybody who is driving past on the road can see it."
The actress Joanna Lumley has unveiled a statue of Peter Pan to recognise the part Dumfries played as birthplace of the children's classic story.