The 44-year-old has guided the club to four Women’s Super League titles.
The 44-year-old has been with the club since 2012 and guided them to four WSL titles, two FA Cups and two League Cups. Hayes’ side were also Champions League runners-up last season.
She said in quotes on Chelsea’s official website: “Everyone knows what this club means to me.
“The work we’ve done together over the last nine years has been hugely rewarding, full of growth of the women’s game, accompanied with winning, which is one of the club’s key values. I really look forward to keep building on the successes we’ve already achieved and I’m delighted to have extended further.
“It’s been a year and a half without fans, so I can’t wait to welcome them back to our home and share with them the wonderful team we’ve built together.”
Chelsea director Marina Granovskaia said: “We are delighted Emma has committed to stay at Chelsea.
“History speaks for itself and we are really proud of what she has achieved in the past nine years, not just at the club, but also for the growth of the women’s game. It is phenomenal and a real credit to Emma for her continued passion, hard work and dedication to the sport.
“We have no doubt there’s more exciting times to come and look forward to watching her take Chelsea Women to even greater heights in the years to come.”
Having retained the WSL trophy and the League Cup in 2020-21, Chelsea fell short of adding the Champions League as they were beaten 4-0 by Barcelona in the final in Gothenburg.
That was a first appearance in the final for the Blues – who reached the semi-finals in 2018 and 2019 – and the first by an English club since Arsenal, who had Hayes as assistant manager at the time, won the competition in 2007.
Chelsea will look to complete a domestic treble in the remainder of the 2020-21 FA Cup, the quarter-finals of which are scheduled for September, with Hayes’ team facing Birmingham away.
The PA news agency understands Hayes has signed a deal with no fixed duration, which either party can end with six months’ notice.