A publication ban was ordered on the evidence being heard before Quebec court Judge Yvan Poulin as Applebaum listened intently and jotted down notes.
He was arrested and charged about two years ago with 14 counts including fraud, corruption, conspiracy and breach of trust involving two real-estate projects in the local district he represented from 2002 until 2012.
Applebaum served as interim Montreal mayor for roughly seven months, beginning in late 2012, after Gerald Tremblay stepped down.
He was the first anglophone mayor of the city in 100 years and his time in office ended one day after his arrest by Quebec's anti-corruption unit in June 2013.
Applebaum, a longtime city councillor and borough mayor before occupying the city's most powerful elected seat, has maintained his innocence and vowed to fight the charges.
His lawyer, Pierre Teasdale, has said his client wants the case heard as quickly as possible.
The accusations relate to his time as borough mayor of Notre-Dame-de-Grace/Cote-des-Neiges, the city's most populous district.
The first witness to take the stand for the Crown was Hugo Tremblay, a former political attache to Applebaum.
At least four other witnesses are expected to follow over the next week and perhaps longer if needed.
Evidence being heard will permit a judge to determine if there is sufficient reason to order Applebaum to stand trial.
The defence has said it won't contest a committal to trial and has opted for a jury trial.
Two others arrested with Applebaum have since pleaded guilty to similar charges.
Saulie Zajdel and Jean-Yves Bisson pleaded guilty late last month to some of the charges they were facing.
Both received suspended sentences, probation, community service and were required to make a donation to community groups.
Zajdel, a longtime municipal politician himself, also dabbled in federal politics as the Tory candidate in the Montreal riding of Mount Royal in 2011, losing to Liberal Irwin Cotler.