Clinton has not yet announced whether she plans to seek the Democratic nomination in 2016. Ready for Hillary is a political action committee formed to support her candidacy.
The group said that Emanuel will headline two Chicago fundraisers on June 5, one for major contributors and the other for grassroots supporters. Tickets for the second event will go for $20.16.
"Hillary is smart, she's determined, and most importantly, she is a champion for the American people," Emanuel said in a statement on the Ready for Hillary website. "I'm proud to make my support for her official, and I'm even prouder to join more than two million Americans encouraging her to run."
Emanuel said he saw Clinton provide effective leadership on women's issues and the fight to provide children with health insurance when he was a White House adviser to her husband. Emanuel later served as President Obama's chief of staff before leaving Washington to run for mayor.
Hard Choices, Clinton's memoir of her four years as secretary of state, is scheduled to be published in June. Her daughter, Chelsea, recently announced she is pregnant.