The Chinese e-commerce giant, racked up gross merchandise value (GMV) of 268.4 billion yuan or over $38.3 billion, setting a new record. The GMV to measures sales across its shopping platforms.
Singles Day, which is also known as "Double 11" because it falls on November 11, is a huge 24-hour shopping event in which thousands of products receive heavy discounts.
While Singles Day GMV was above market forecasts, they didn't meet Ma's expectations.
"What I want to tell you is that the sales of Singles Day this year hasn't even reached my expectation," he said.
Still, Ma said he was happy that the GMV surpassed analyst estimates.
"11.11's numbers surpassed forecast and went beyond what most people expected from today's economy," Ma said at the 5th World Zhejiang Entrepreneurs Convention on Wednesday.
"Wall Street predicted that 11.11 would grow by around 20%, a sign that China's consumption is weak and the economy is slowing down. But our numbers actually grew 25.7%."
In a video circulating on Chinese social media, Ma added: "There are multiple reasons, one of them is that the weather is too hot. Clothes sell better when it's cold. Another reason is that it's a Monday."
The Alibaba co-founder said he hoped the government would give people a half day off of work for future Singles Day events.
Alibaba was not immediately available for comment.
Ma's comments come as Alibaba readies itself for a secondary listing in Hong Kong in which it could raise $13 billion, a source with direct knowledge of the matter told CNBC.