Yahoo is trying to reduce its dependence on adverts
"We are very pleased to be joining Yahoo," said HotJobs chief executive Dimitri Boylan.
Monster.com's owner, TMP Worldwide, had declined to reply by raising its bid, saying it had offered "full and fair value" for HotJobs.
CIBC World Markets analyst John Corcoran said Yahoo's takeover was "interesting and bold", and may turn out to be a bargain.
"A year from now you may look back and say Yahoo was able to buy HotJobs at the dip."
HotJobs should help Yahoo to diversify its business, thereby reducing its reliance on advertising.
Stock market moves
TMP Worldwide's initial offer had been more valuable than Yahoo's offer, but since the company had wanted to pay with shares it was vulnerable to stock market moves.
When the offer was made, it valued HotJobs at $12.20 per share, but as TMP's share prices slid the value of the offer also declined to $9.19 a share.
Yahoo's offer values HotJobs at $10.50 per share.
HotJobs will pay TMP Worldwide a $15m break-up fee plus $2m in expenses.
Yahoo expects to close the HotJobs deal early next year.
Soon afterwards, analysts believe HotJobs' revenues could be in for a rise as an anticipated economic recovery in the US could bring a boom to the online recruitment market.
HotJobs collect CVs from jobseekers and charge companies to advertise vacancies and to access its database of about 5 million CVs.
Monster's CV database is about three times as large, and the company has entered into key distribution deals with America Online and Microsoft's MSN network.
HotJobs is not likely to wrestle the leadership in the online job postings market from Monster, said Mr Corcoran.
Hot Jobs shares fell while both Yahoo and TMP Worldwide rose.