She was born in a poor family in Hannibal, Missouri. Upon adulthood, she moved to Leadville, Colorado where she married a rising mining engineer by the name of James L. Brown. The couple came into enormous wealth when James' engineering efforts proved instrumental in a major gold strike at the Little Jonny Mine. However for all their new wealth, the Browns were still dismissed by the social elite for their poor origins.
Maggie Brown was taking in a European tour when she learned that grandson was ill. She immediately booked first class passage back to the USA on the Titanic. When the ship collided with the iceberg and began to sink, Maggie Brown was put on a lifeboat and lowered to the water. In the midst of the crisis, the one seaman on the boat had panicked and refused to do anything since he was convinced the lifeboat was doomed to be sucked down when the ship sank. Maggie Brown took command and had the passagers row to safety and kept their spirits up by whatever efforts she could manage.
When the RMS Carpathia arrived to rescue the survivors, Maggie Brown assisted with the rescue efforts. She helped with the rescue effort's organization, preparing survivor lists for outside communication and raised funds with other rich survivors to help the destitute portion of the survivors and collected $10,000 by the time the ship made port in New York City.
For her calm action in the disaster, the media acclaimed her as one of the heroines of the hour. A quote from her that this whole episode was that it was typical Brown family luck to be unsinkable. That word became immediately attached to Maggie Brown and she became known as the Unsinkable Maggie Brown for the rest of her life.
A later Broadway Musical, The Unsinkable Molly Brown, presented a fictionalized account of her life while changing her name to Molly, but it ensured her eternal connection with the infamous Titanic sinking.