The Carlton Tavern, in Maida Vale, was bulldozed last month while under consideration for listed status.
Its owners have been told to rebuild it brick-by-brick.
Westminster City Council's planning director John Walker said: "The council will not tolerate any flagrant disregard of the planning system."
Backing the move Robert Davis, deputy leader of the council, said: "We cannot live in a city where unruly developers can just knock down buildings as and when they please.
"Westminster is home to the West End, not the Wild West."
The Carlton Tavern in Maida Vale was the only building left standing in the street after the area was bombed in WW2.
An application to pull down the building and replace it with a new pub at ground level and residential units over several floors was refused by the council.
Historic England - previously known as English Heritage - was recommending the 1920s building for listed status.
Landlady Patsy Lord said she had no prior warning of the demolition and was only called out to move her son's car away from the building on the morning the bulldozers arrived.
Historic England said the tavern was built in 1920 in the Vernacular Revival style by Frank J. Potter.
It was commissioned by Charrington & Co brewery at a cost of Â£11,600 and replaced an earlier pub on the site dating from the 1860s that was destroyed by a German Zeppelin bomb on 19 May 1918.
The owner of the pub has so far been unavailable for comment.
The owners of a west London pub that was demolished without planning permission to do so, have been ordered to rebuild it within 18 months.