María del Rosario Montt Goyenechea was born in Chile, the daughter of Filiberto Montt Prado (1758–1838) and María de la Luz Goyenechea de la Sierra, and part of the prominent Montt family, originally from Catalonia.

Her older brother was politician José Anacleto Montt Goyenechea (1802-1867).

Because he was the target of attempted assassinations, she was the only person allowed to shave her husband's face or cut his hair.

Montt's home in Santiago was declared a national historic site in 1981.

[5] From 1891 to 1896, her nephew Jorge Montt was president of Chile.