Chloe Jarvis, 13, had an emotional meeting with Roland Hauessler, 50, in London at an event to increase the pool of potential donors.
Chloe, from Shotts, North Lanarkshire, was diagnosed with leukemia in 2008 and is now close to being given the all-clear thanks to the transplant she received a year later.
The operation was only possible after doctors found a 100% match in Mr Hauessler's donated stem cells.
Chloe said: "When I got told I was going to need a stem-cell treatment, I thought that it was over but it wasn't."
Chloe was diagnosed with acute myeloid leukemia in April 2008 and received her transplant in February 2009.
She and Mr Hauessler, from Germany, have kept in touch but met for the first time today.
Mr Hauessler, from Nuremberg, said: "It can be so easy to save a life."
Sandra Bothur, director of Delete Blood Cancer UK, said: "We are delighted to be launching Delete Blood Cancer UK, so we can start on our work to increase the pool of potential stem cell donors."