He said people could continue to go online and make donations at: givealittle.co.nz/cause/teahoworldride/
The funds raised would go towards research that accelerates the development and testing of new drugs and diagnostic tools that directly assist clinicians and their patients.
Mr Nicholson was inspired to make the journey after the death of a friend from cancer.
He has had to dip into his own pocket for air fares, and has stayed with friends along the way.
The trip started on August 12 when he flew from Auckland to Vancouver.
From there, he cycled across Canada and the United States, through Europe to India and through Southeast Asia, across Australia, then the length of New Zealand back to Auckland.
Mr Nicholson completed the 29,179km ride in 123 days, one hour and six minutes - about two days faster than the Guinness world record.
However, it could be several weeks before his achievement is officially recognised as a Guinness world record.
"I feel a sense of relief now that it's over. The body needs a rest. I'm very glad not to be riding tomorrow, but the legs will probably twitch and want to go anyway.''