The Edinburgh-based former policy boss at the Better Together campaign was diagnosed with the disease two years ago at the age of 29.
He launched GordonsFightback.com to raise funds for research and lobby for better care for people with MND.
Almost 6000 donations later he has now reached the £500,000 mark. Events which contributed to the success included high profile comedy gigs, marathons, pub quizzes and bake sales.
Gordon said: “This money will change lives. It makes me immensely proud to know that research is happening today, as we speak, that simply would not have been possible without these vital funds.
“To everyone who has helped us reach this incredible milestone: thank you. Together we have brought forward the day we live in a world free from MND.
“It might be too late for me, but by investing in research we can, we must and we will find a cure for future generations.”