Marianne Faithfull, who went from being a fresh-faced, feather-voiced pop star, as well as muse and girlfriend of Mick Jagger, to a homeless heroin addict, only to re-emerge radically altered in her early 30s as a critically acclaimed chanteuse singing songs of dark honesty, died on Thursday in London. She was 78.

Her death was confirmed by a spokesperson, who did not cite a cause.

The roiling dramas in Ms. Faithfull’s life, along with the starry circles she moved in during the Swinging Sixties and the unvarnished power of her later music, turned her into a nearly mythic figure — a symbol of survival and transformation. It’s a role she at first rued but later came to relish.

“What I’ve been trying to do, and I think I’ve done it rather well, is bring the persona — or what was a false persona in the beginning — and me together,” she told the British newspaper The Independent in 2008.

But the road to get there was long and perilous. It involved a miscarriage, the temporary loss of her only child in a custody battle, a suicide attempt, several stints in rehab and a 1967 drug arrest — also involving the Rolling Stones — whose salacious and sometimes erroneous details generated reams of heated headlines in Britain.

Still, when Ms. Faithfull finally found a bold new path for her music, starting in 1979 with the new-wave-influenced album “Broken English,” she earned the kind of broad respect she had never before enjoyed, inspired by the brutal truth of her material and the scarred gravity of her voice.

“I’ve got the right voice for me,” she told The Independent of her new sound. “It gives an edge to everything.