Stuart Hindes, 53, from Leeds, had started his charity swim about 03:00 BST on Sunday from Dover harbour.
Mr Hindes said there was "quite a swell" but he had started to catch the tide and had taken his seasickness medication.
"There's only so much you can put up with when you are retching," he added. His swim ended after about four hours.
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Mr Hindes described conditions as like being in a washing machine and said he had been battling seasickness after about 20 minutes of the attempt.
"It was tough I gave it everything I could before I got in the boat," he said.
The shortest route between Dover and Calais is about 21 miles (33km) but a swimmer covers a longer distance due to water currents. Mr Hindes had planned to be in the water for about 16 hours.
The fastest swim has been completed in about seven hours and the slowest in nearly 27 hours, according to the Channel Swimming Association.
When asked whether he would attempt the swim again, Mr Hindes said: "It's too early to say, I'm still hurting."
Mr Hindes had been part of a relay team of six swimmers that completed the cross-channel swim in 2011.
On his solo effort Mr Hindes was raising funds for mental health charity Mind and Clic Sargent, a cancer support charity for children, young people and their families.
He has raised Â£3,290 for CLIC Sargent so far, the charity said.
A swimmer had to abandon an attempt to cross the English Channel after a severe swell made him seasick.