They believed this was the only way to bypass the expected Labour opposition to the full motion - but an amendment on Palestinian rights stopped any rebellion.
The debate began with two speeches from anti-Zionist activists - David Kaye and Michael Coleman, who stressed he was from an "Orthodox Jewish family" - which both received applause from the floor.
Both spoke against the IHRA motion claiming it exaggerated the extent of hate crime against the community and stifled debate on Israel/Palestine.
Labour councillor Neil Nerva, who represents the Queens Park ward, took to the floor and spoke in support of the motion and a separate motion condemning the rise of all hate crime.
Attacking the argument that antisemitic incidents in the borough were dwarfed by attacks on Muslims and homosexuals, Mr Nerva, a member of the Jewish Labour Movement, said: "As councillors we have been sent a letter by the Board of Deputies that reminds us of the need to pass both motions.
"I think they speak for all people, whether they are Jewish or non-Jewish in Brent."
John Warren, the new leader of the Brent Tory group, gave a short speech in which he highlighted the need for "harmony" and "good community relations" in the borough.
But in an impassioned address Mr Davidson insisted it was "essential for Brent Council to join with 100 other local authorities who have signed up to the IHRA definition”.
He added: "Antisemitism is at its highest level since records began. It is extremely serious.
"Furthermore I'd like to ask members what is it about the guidelines (with the definition) that they could possibly object to?
"As Brent councillors we have gladly all condemned discrimination including all types of racism that exist in our borough.
“There is no difference whatsoever in supporting this motion than there is in supporting all the other motions we have supported on a cross-party basis."
Mr Davidson, from the Brondesbury Park ward, also reminded the meeting that Brent had "historically" had a problem with antisemitism.
Labour Willesden Green councillor Tom Miller attacked the "regrettable line of argument" from some opponents of the definition which he said "implied a hierarchy of bigotries”.
A letter sent by the Board to all Brent councillors had called for them to adopt the IHRA motion "and its appended list of examples which give clarity about what does and does not constitute contemporary antisemitism".
The letter addressed concern that the motion would stop criticism of Israel, saying: “Criticism of any government, including Israel's, is a legitimate and necessary part of democratic discourse."
After both motions were passed, some critics attempted to claim Brent had passed a "watered down" version of the IHRA definition.
But senior figures in both Conservative and Labour group's pointed to the original Home Affairs Select Committee assessment of the IHRA definition.
The committee’s report spoke of the need for "additional caveats" before adoption by the UK government.
One senior Brent councillor added: "It may look messy but this vote was a coup for supporters of the IHRA definition in Brent.
"You have to remember this is the borough of Ken Livingstone and others like him in the past.
"There may have been political manoeuvring on the night - but the motions were passed."
Outside the hall around a dozen far-left anti-Zionists looked dejected as they discussed their failure to persuade the council to reject the motion.
Phil Rosenberg, Board of Deputies public affairs director, said: “We were very pleased that the motion put to Brent Council on the IHRA Definition of antisemitism was passed unopposed.
"We wrote to every councillor prior to the debate and were delighted with the response. The clear message on antisemitism being unwelcome in Brent, or anywhere in our society, was a very good Rosh Hashanah present for the Jewish community.”
