Roenneberg, who was trained in Britain during World War II, led a six-man team for Operation Gunnerside in an attack on the Norsk Hydro heavy water production plant in Vermok, Norway.
His actions were dramatized in the Franco-Norwegian 1948 film "Operation Swallow: The Battle for Heavy Water" and by US movie "The Heroes of Telemark", starring Kirk Douglas.
Roenneberg, 93, was presented with the flag at a ceremony in London attended by Norwegian Defence Minister Anne-Grete Strom-Erichsen.
Norwegian soldiers laid wreaths on the Special Operations Executive (SOE) monument, marking 70 years since the successful mission.
"I think it's an amazing thing to stand and hold the flag that was probably on the pole in 1943," he told AFP. "It's amazing."
Describing his celebrated mission, Ronneberg recalled: "We had the feeling that it must be some very special thing since the British started planning our trip immediately after they had lost 41 people. So it had to be important."
Strom-Erichsen called it a "very important ceremony.
"It's for a very important operation during Second World War which if they hadn't succeeded could have been terrible, not only for Norway but for the outcome of the Second World War," she told AFP.
"It is of course a remembrance of brave men and women and also the strong ties between UK and Norway."