WASHINGTON — Joseph R. Biden Jr. said on Thursday that he had raised $22.7 million in the fourth quarter of 2019, a significant improvement from his lackluster fund-raising performance in the previous three months.

Mr. Biden’s total, for the period from October through December, far exceeded the $15.7 million that he had raised during the third quarter. It was his largest quarterly haul so far, surpassing the $22 million he brought in during the second quarter.

But Mr. Biden’s fourth-quarter total was much smaller than that of Senator Bernie Sanders of Vermont, whose campaign announced earlier Thursday that it had raised more than $34.5 million in the quarter. Mr. Biden, the former vice president, also lagged behind Pete Buttigieg, the former mayor of South Bend, Ind., whose campaign revealed on Wednesday that it had brought in more than $24.7 million. Another leading candidate, Senator Elizabeth Warren of Massachusetts, has not yet announced her fund-raising total.

While Mr. Biden’s fund-raising rebound did not vault him to the top of the Democratic pack, it still offered a reassuring sign for his supporters as the primary race heads into the final weeks before the Iowa caucuses in early February. His campaign said its online fund-raising doubled in the fourth quarter, and that more than half its donors in the quarter gave to the campaign for the first time. The average donation in the quarter was $41, the campaign said.