Fifty years later, the hotel is celebrating their fabled experiment in pacifism with a series of special events including guided tours of the couple's room.
"We're still talking about it 50 years later, but at the time we had no idea the impact that it would have," Joanne Papineau, spokeswoman for the hotel, told AFP.
"After the couple left, for years we didn't talk about the bed-in, but then John was murdered, other wars continued and people started showing up wanting to see where it all happened," she said. "Many years later, they suddenly found meaning in what the couple had done."
From May 26 to June 2, 1969, Lennon and Ono received journalists from around the world who interviewed the couple in bed, as well as fans and fellow artists who helped to create a chirpy ambience and send a simple message: Stop the Vietnam war.
The idea derived from sit-ins, in which protestors sit in front of or inside an establishment until their demands are met or they are arrested.
Amid this merry chaos and with limited technical means, Lennon composed and recorded his famous hymn to peace, "Give Peace a Chance."
His entourage, which included psychedelic drug advocate Timothy Leary and writer Allen Ginsberg, not always singing in tune, provided the chorus. The song would later be remixed in a professional sound studio.
"This is certainly one of the most remarkable and influential songs of contemporary music," Genevieve Bornesaid, host of the upcoming festivities, told a news conference on Thursday.
"This bed-in for peace was also one of the first acts of activism by artists."
'Lennon changed my life'
The special events at the Fairmont The Queen Elizabeth Hotel in Montreal will kick off on Saturday and continue through Lennon's birthday on June 9.
They will include the unveiling of an exhibit of photographs taken during the bed-in, guided tours of the famous Room 1742, a "hippie" night and a concert for peace.
The Phi Foundation will also host an exhibit of the works of the widow of Lennon, the Beatles singer who was tragically gunned down outside their New York apartment in 1980.
The couple had actually rented four adjacent rooms in the hotel (1738, 1740, 1742 and 1744) for their stay in 1969.
The rooms have since been combined into a single 1,400-square-foot suite and renovated, but in keeping with the original design. Mockups of two original hand-painted "Hair Peace" and "Bed Peace" signs adorn the windows.
Carmel Masse, a 57-year-old Canadian fan of John Lennon and the Beatles booked the suite for the night from Sunday to Monday.
"Lennon changed my life," he told AFP. "When I saw John Lennon bearded in Montreal, with his guru side, looking like Jesus Christ, his journey intrigued me."
Lennon's pacifist message would further seduce and inspire him.
"To rent this suite is like saying 50 years later, 'Thank you for making me a better person.'"