Suppliers who spoke to OLN described the retailer's requests as "bad business practice" and "unreasonable".
The retailer asks suppliers for voluntary contributions - ranging from three- to four-figure sums - every year. This year the contribution has been bundled in with the regular listing fee to ensure all suppliers contribute equally.
The event takes place on Sunday at the five-star Grosvenor House hotel and will attract more than 1,000 people.
Those who refuse to pay the money - which Majestic describes as a "tiny" extra amount on top of the existing invoices - face delisting.
Suppliers told OLN that they feel under pressure to pay, and that the contribution is deducted from Majestic's payments to them if they don't cough up.
One supplier said he was still deciding whether or not to pay the money. "This is not a practice we endorse. They don't fund our Christmas party," he said.
Another said Majestic's request for money was unreasonable. "If we thought that was reasonable, we would be asking our suppliers to pay for our parties. It stinks," he said.
Some suppliers will refuse to pay - last year, Majestic issued credit notes to suppliers who complained when money was taken from them anyway.
A Majestic spokeswoman said: "The party is a reward for all our staff and their partners for their hard work. It's something that our suppliers have always helped us with by supplying the alcohol."
Majestic chief executive Tim How said the tradition of contributing to the party predated his tenure and was a matter for Majestic and the companies involved.