The amphibian survived being packaged in cellophane in Colombia, shipped across the Atlantic and enduring a stop-over in Holland.
Ruth Marriner then discovered it peering out of some tropical foliage that had been delivered to her shop in Blackburn, Lancashire.
Believed to be a poison dart frog, it is now being housed at Blackpool Zoo.
The tiny brown and yellow frog, which is about 3cm (1.2in) long – about the size of a 50p coin.
Investigations to ascertain the exact species are currently being carried out, but some experts believe it could the phantasmal poison frog – the most deadly of its kind.
Poison dart frogs earned their name after being used to make weapons by the indigenous people of the Americas.
They would use the frogs’ toxic secretions to poison the tips of blowdarts and fire them at the enemy.
Mrs Marriner, 46, who owns Ruth Marriner Flowers, said: “One of the florists, Debbie Wilding, was unwrapping some of the foliage we had been sent.
“She felt it move, jumped back, and screeched, ‘there’s a frog in there’.
‘Goggly eyes’
“We all started laughing – you don’t get frogs in foliage we said. Then as we started to investigate and we saw these big goggly eyes.
“Luckily, the sister-in-law of one of the girls, Louise, works at local agricultural Myerscough College.
“We rang her, and she told us not to touch it and ring Defra.”
The florists were told not to go near the little creature and an expert from the college’s small animal team came to take it away from the shop in Cherry Tree within the hour.
The mother-of-four added: “I’ve been a florist for 30 years and I’ve never seen anything quite like it – we often get bugs and things but nothing this exotic.
“I am just relieved we didn’t sell the flowers with the frog buried in the packaging, it could have been a totally different story then.
“We’re definitely a bit more wary when unwrapping our tropical flowers now.”