Azhar’s JeM, based in Pakistan, claimed responsibility for a suicide bombing in the Indian-administered Kashmir town of Pulwama last month that killed at least 40 Indian security forces personnel.
The attack, and subsequent claim, led to India accusing Pakistan of “controlling” the attack.
The subsequent spike in tensions between the nuclear-armed neighbours saw both countries bomb each other’s territory and at least one Indian fighter jet shot down, with its pilot captured by Pakistan.
The pilot’s release shortly afterwards led to a decrease in tensions, but India continues to demand action against JeM.
Since last week, Pakistan has arrested at least 44 people – including Azhar’s son and brother-in-law. It also shut down scores of schools and mosques associated with JeM and the Lashkar-e-Taiba armed group, the interior ministry has said.
Wednesday’s vote at the Security Council will be a test to see if Pakistan is willing to have Azhar’s name added to a United Nations sanctions list that would see him subject to an assets freeze, international travel ban and arms embargo.
JeM is already sanctioned by the UN with the group enlisted into the sanctions regime in October 2001, for “participating in the financing, planning, facilitating, preparing or perpetrating of acts or activities by, in conjunction with, under the name of, on behalf or in support of, supplying, selling or transferring arms and related materiel to or otherwise supporting acts or activities of al-Qaeda, Osama bin Laden and the Taliban,” according to the UN website.
Previous votes to list Azhar have consistently been blocked by China, which holds veto power at the Security Council.
Azhar formed JeM after his release from an Indian prison in return for 155 hostages held on board an Indian Airlines flight that was hijacked to Kandahar, in eastern Afghanistan.
The group has carried out a series of high-profile attacks against Indian targets since its formation, notably attacks on the Indian-administered Kashmir legislative assembly and the Indian parliament in 2001, an attack on an Indian airbase in Pathankot in 2016 and, most recently, the Pulwama attack last month.
For years, Azhar moved freely around Pakistan, organising sermons and recruitment activities on Pakistani soil.
He was arrested shortly after the Pathankot attack under anti-terrorism laws, but was never formally charged.
On Monday, China’s foreign ministry said it was considering the issue, but urged “responsible and serious discussions”.
“China will continue to communicate and work with relevant parties in a responsible manner so as to properly resolve this matter,” said foreign ministry spokesperson Lu Kang.
“Only by making a decision through responsible and serious discussions can we find a lasting solution.”
Last week, Pakistan’s Information Minister Fawad Chaudhry told Al Jazeera that Azhar was a marginal figure in JeM and that listing him would have limited value.
“Masood Azhar is now more of a symbolic thing,” he said. “Masood Azhar is now too ill, frail and old.”
Chaudhry said Pakistan was “debating” whether to withdraw its objection to the move.
Last week, Pakistan added Jamaat-ud-Dawa and Falah-e-Insaniat Foundation, the humanitarian relief wings of Lashkar-e-Taiba, to its list of banned “terrorist” organisations.
Analysts say there appears to be limited potential for Pakistan to block its veto, exercised through China.
“Pakistan does not have a vote at the United Nations Security Council, and what I saw from the Chinese statement there does not appear to be a major change in their stance,” said Zahid Hussain, an Islamabad-based security analyst.
“They probably want a more comprehensive resolution [mentioning the situation in Kashmir], and if Masood Azhar’s name is included in it, then they wouldn’t mind.”
Follow Al Jazeera’s Asad Hashim on Twitter @AsadHashim