Researchers widely believed the asteroid cut off the food supply in the ocean 65 million years ago.
But the new study has found evidence to suggest some algae and bacteria survived and acted as a sinking "trickle of food" for sea creatures.
The research analysed fossilised shells from South Atlantic drilling cores.
It showed deep sea creatures managed to survive despite the fact dinosaurs, giant marine reptiles, invertebrates and microscopic organisms became extinct.
The study, led by researchers from Cardiff University's School of Earth and Ocean Sciences, has been published in the Geology journal.
PhD student Heather Birch, who led the research, said the findings answered "one of the outstanding questions that still remained regarding this period of history".
How deep sea creatures survived the asteroid strike thought to have wiped out dinosaurs has been uncovered by experts at Cardiff University.