The fashion designer - who committed suicide by hanging last week - bequeathed all of her estate, including her $8 million New York condo, to her grieving lover in her final will, which was obtained by the New York Post newspaper.
In addition to the lavish home, L'Wren has also given Mick, 70, all of her expensive jewellery, clothing and more.
She wrote in her will: ''I give all my jewellery, clothing, household furniture and furnishings, personal automobiles and other tangible articles of a personal nature ... to Michael Philip Jagger.''
The will was signed by the 49-year-old ex-model on May 23, 2013, in Beverly Hills, California.
L'Wren also insisted that she was ''intentionally'' ignoring her siblings - including sister Jane Shane, 53, who she hadn't spoken to in six years - in her will.
The news is surprising as she had made her older brother Randall Bambrough, 58, co-head of her fashion company LS Fashion Ltd. just last year.
She wrote in the will: ''Except if otherwise provided in this will, I have intentionally omitted to provide herein for any of my heirs living at the date of my death.''