The Hoops fought back from a two-goal deficit against Kazakhstan champions Shakhter Karagandy to win 3-0 on Wednesday night at Parkhead.
Neil Lennon's men reached the last 16 of the competition last year and Doncaster believes Celtic have again helped to enhance the reputation of the game north of the border by securing a seat at Europe's top table yet again.
He said: "It's absolutely tremendous, a real boost for the entire game in the country.
"Huge credit goes to Neil Lennon and his club for what they have achieved.
"Having to go through three qualifying rounds is extremely tough and it's a great boost for the game in this country.
"There is a great amount to look forward to in the season ahead.
"It does a whole lot of good to the reputation of individual clubs but also the entire league and the industry in this country."
Despite reaching the knockout stages, before eventually exiting to Juventus last year, Celtic had to overcome Cliftonville, Elfsborg and Shakhter just to reach the group stages this time.
Doncaster added: "They are the rules that UEFA lay down.
"The fact is that our co-efficient over the last couple of years has dipped after a number of years where performances across the country were below par.
"What Celtic achieved last year was terrific and to go through to the group stages this year is a great boost for everyone.
"The more that happens, the more it boosts the co-efficient and the more places you get in Europe.
"So it can be a virtuous circle or a vicious circle and we are coming off the back of a number of years where Scottish teams overall were under performing in Europe."
Doncaster was speaking at the draw for the third round of the Scottish League Cup at Easter Road.
The cup competition, as well as the newly-formed SPFL, still does not have a sponsor.
Doncaster said: "We have only been in existence for a number of weeks as a combined entity so we are talking to a number of people.
"Clearly we are working hard to bring in the best financial contribution that we can to these competitions.
"I'm not sure deadlines are particularly helpful. I think it's a question of working as hard as you can to get talking to as many people as you can who want to be involved."
Doncaster says a summer of uncertainty over league reconstruction hampered hopes of getting a sponsor on board sooner.
He added: "All sponsors need certainty as a bare minimum. They need to know what exactly they are investing in and what they are getting in return.
"Up until June 27, I don't think any of us really knew exactly what would happen this year.
"Work is ongoing to ensure that, with that clarity, we partner with brands that want to be part of the exciting story that is Scottish football."
There was one financial boost for SPFL clubs today when the Scottish Government announced a £650,000 package of support linked to the League Cup.
The funding is designed to help clubs "create new opportunities for people to participate in sport and physical activity; become Community Sport Hubs that provide a home for local clubs and sports organisations; and continue with youth employment and training initiatives".
Sport minister Shona Robison said: "Football clubs do so much in their communities, from inspiring young people with positive role models to giving adults the support and facilities to get active. With football now the top team sport for girls, the Scottish League Cup is an ideal way for clubs to welcome more people into the football family.
"So our support will help Scottish Professional Football League clubs expand their community engagement programmes to get even more people of all ages involved, whether by playing football, using club facilities to get active or giving young people new skills."