Bromwich, who has also captained New Zealand, will join the Dolphins on a two-year deal from their inaugural season in 2023.
The prop will turn 35 halfway through the final year of his contract.
Bromwich has played all of 272 NRL games at the Storm and will be a huge chance of becoming the Dolphins first captain.
The Kiwi is the fifth player to join the Dolphins since they were announced as the NRL’s 17th team last October.
Bromwich will join Storm teammate Felise Kaufusi, Eels forward Ray Stone, Broncos flyer Jamayne Isaako and young gun Valynce Te Whare.