Towels were wrapped around the dolphins' teeth
Mongolian herdsman Bao Xishun was called in after the dolphins swallowed plastic used around their pool at an aquarium in Fushun, north-east China.
Attempts to use instruments failed as the dolphins contracted their stomachs.
Guinness World Records list Mr Bao, 54, as the world's tallest living man at 2.36m (7ft 8.95in).
Veterinarians turned to Mr Bao after attempts to extract the plastic shards at the aquarium in Fushun, Liaoning Province, had failed.
The mammals had lost their appetite and were suffering depression, aquarium officials said.
The heads of the dolphins were held back and towels wrapped around their teeth so Mr Bao could not be bitten.
He then extended his 1.06m-long arm into the mammals' stomachs.
Chen Lujun, manager of Royal Jidi Ocean World, said Mr Bao was successful and the dolphins were "in very good condition now".
Local doctor Zhu Xiaoling told the state media agency Xinhua: "Some very small plastic pieces are still left in the dolphins' stomachs.
"However the dolphins will be able to digest these and are expected to recover soon."
Mr Bao was confirmed as the world's tallest living man by Guinness World Records last year.
He overtook the previous holder, Radhouane Charbib of Tunisia, by just 2mm.Guinness World Records say Mr Bao was of normal height until 16 but then put on a spurt that doctors were unable to explain, reaching his full height in seven years.