But it still beat both the company's and market's expectations.
The world's largest contract chipmaker includes tech giants Apple and Nvidia as customers.
It has benefited from a boom in artificial intelligence applications.
Revenue in the final three months of last year came in at $20.1 billion - slightly up from a year before.
Both TSMC and analysts had predicted lower than that.
But December proved a challenging month.
TSMC reported revenue fell 8.4% year-on-year, sharply worse than in the previous month.
The firm did not provide any details or forward guidance in its brief revenue statement.
It is due to report fourth-quarter earnings on January 18, when the firm will also update its outlook for the current quarter and the year.
