The new numbers, including openings across all sectors for that month, were released as part of the Job Openings and Labor Turnover Survey, which was updated by the Bureau of Labor Statistics on Tuesday.
The increase is a sign that the labor market is holding on despite the higher interest rates, although on balance, job openings have largely fallen since peaking nearly two years ago.
Hires also rose slightly in December, to 5.6 million. That comes after a notable decline in hiring the month before.
About 3.4 million workers quit their jobs in December, little changed from the month before. The figure is equivalent to about 2.2% of the workforce.
The “quits rate” measures the number of people who voluntarily left their jobs and