John Beeden, 53, set off from San Francisco on 1 June and rowed for an average of 15 hours a day.
He had hoped to reach Cairns in north-east Australia weeks ago, but was slowed down by bad weather.
Mr Beeden, who rowed across the Atlantic four years ago, said there were times when he didn't think he could go on.
"To be the first person to achieve something on this scale is incredible really, and I haven't processed it yet," added Mr Beeden, who is originally from the northern English city of Sheffield but now lives in Canada.
He thanked the people of Cairns for a "brilliant reception" after 209 days at sea.
There have been some nine successful rows across the Pacific Ocean.
Some of those crossings were completed in stages while others left from South America, rather than from North America as Mr Beeden did.
John Fairfax and Sylvia Cook crossed the Pacific in 1971-72, leaving San Francisco and arriving at Hayman Island in Australia.
They became the first people to cross the Pacific and Ms Cook became the first woman to cross any ocean. They stopped along the way.
In 1983 Peter Bird set off on a solo rowing trip across the Pacific from San Francisco. He had to be rescued by the Australian navy 294 days later, coming within reach of the Great Barrier Reef.
Mr Beeden's wife Cheryl said: "He's an amazing guy, he's different than a lot of other people - he'll always fight to get the mile when he's having a bad day... he'll always be rowing.
"Always knew he could do it, it just took a lot longer than we expected and just glad that he's home and safe."
She added: "I kind of think it's like childbirth because he says he's not going to get in another boat for a while - but I am sure in a couple of weeks he'll be having some other adventure, and I will have to restrain him a little bit."
A Briton has completed the first non-stop solo row across the Pacific from North America to Australia.