Yingluck was found guilty of abusing her power, further deepening the political crisis that has led to violent protests and brought the economy close to recession.
The decision is bound to anger supporters of Yingluck, but the court did allow ministers not implicated in the case against her to stay in office.
After the ruling, commerce minister Niwatthamrong Boonsongphaisan, who is also a deputy prime minister, replaced Yingluck. The cabinet said the caretaker government would press ahead with plans for a July 20 election.
Yingluck said she did nothing wrong while in office. Meanwhile, thousands of her Red Shirts supporters say they will descend on Bangkok on Saturday to protest against the Constitutional Court’s ruling.
More than 25 people have been killed and hundreds injured since anti-government protesters took to the streets last November.
So, is Thailand poised for more violence?
Presenter: Mike Hanna
Sean Boon-pracong, adviser at the prime minister's office
Kasit Piromya, an opposition member of parliament, and deputy chair for the Democrat Party's policy committee
Kriengsak Chareonwongsak, president of the Institute of Future Studies for Development