The Respect Party leader, who lost his seat as Bradford West MP to Labour last month, outlined a range of policies designed to clamp down on what he described as the “social cleansing” of the city.
The 60-year-old said he would compulsory purchase residential properties left vacant for at least one year, and said planning consent would not be granted to any new-builds unless at least 50% was social or affordable housing.
Speaking at the Ethical Society in Holborn, central London, he said: “I will tackle the housing crisis as my number one priority.
“We will compulsory purchase - and we have the power to do so - any house that has been unlived in, without a proper excuse, for one year or more.”
He said “house prices and backbreaking rents are driving people further and further to the edge of London, literally and metaphorically”.
In a wide ranging speech - followed by a question-and-answer session featuring pre-submitted queries and as well as questions from Respect supporters in the crowd - Mr Galloway vowed to tackle white-collar crime in London’s Square Mile, and suggested an annual Battle of Britain weekend - “a mixture of celebrity and fun”, and a recreation of the spirit of the Blitz.
He described the “three main political parties” as “three cheeks of the same arse”, and described current mayoral incumbent Boris Johnson as a “blond buffoon”.
Around 150 people were present in the audience for the two hour event.
He announced his intention to run for the post at the end of May, pledging to “build a city that benefits everyone, not just those dripping in gold”.
The maverick left-winger is no stranger to controversy.
He was widely criticised two decades ago during a visit to Iraq in which he apparently praised tyrant leader Saddam Hussein for his courage - comments he said referred to the Iraqi people - while he was also an outspoken opponent of the 2003 invasion of the war-torn country.
He went on to appear in Celebrity Big Brother, and also recently spoke in support of corrupt former Tower Hamlets mayor Lutfur Rahman who was removed from office after being found guilty of electoral fraud.
Labour has announced six candidates would vie to represent the party at the London mayoral elections. They are Dame Tessa Jowell, MPs Sadiq Khan, David Lammy, Diane Abbott and Gareth Thomas, and journalist Christian Wolmar.