The European Union leader was stumbling so much that world leaders including the presidents of Finland and Ukraine, and the Dutch Prime Minister, were forced to hold him up.
Footage from the summit shows the 63-year-old being held up as he makes his way down the stairs.
But as Mr Juncker attempts to walk he stumbles backwards and loses his balance once again.
The European Commission President then had to be held at the arm in an effort to steady himself.
Prime Minister Theresa May walked past Mr Juncker and grinned, seemingly unaware that the European Commission President was struggling to stand unaided.
Jean-Claude Juncker struggled to stand unaided
It is a problem in a sense that he sometimes has these pain attacks
Mr Juncker was attending a gala at the Nato summit in Brussels attended by US President Donald Trump and First Lady Melania Trump.
Following the event, Dutch Prime Minister Mark Rutte said: “He doesn’t have a serious health problem as far as I am aware of but he does have a back problem for some time.”
He added: “It is a problem in a sense that he sometimes has these pain attacks.”
Mr Juncker has previously said he suffers from sciatica which can sometimes affect his movements.
The European Commission President’s office declined to comment due to privacy concerns.
During the Nato summit, President Trump launched a furious tirade against Germany and branded it a “captive of Russia”
The US President vented his anger on the opening day of the Nato summit in Brussels where he demanded that countries like Germany pay their fair share in defence spending.
In a sign of the rows which are expected to take place over the two day summit, Mr Trump questioned why Germany pays billions of dollars to Russia for gas supplies but then demands that the US defends it from Russia.
“I think it’s inappropriate,” he said repeatedly in an uncompromising conversation with Nato Secretary General Jens Stoltenberg.
The UK has been one of the few Nato members to meet the minimum of spending two percent GDP on defence and security.