The family announced the news in a statement on Tuesday, local time. She was 92.
She had been dealing with heart and respiratory disease for some time and recently declined further medical treatment, saying she wanted to spend her last days in "comfort care" with her family.
Her husband George H W Bush Snr was elected US President in 1989. Aged 93, he is the longest-lived US president. Her son George W Bush served two terms between 2000 and 2008.
