She was born in Essex, the eldest of nine children of a clergyman. She was educated at Dickinson's Academy in London. In 1851, at the age of seventeen, Osborn began showing her work in the annual Royal Academy exhibits, and continued to do so over a span of four decades (to 1893). Her pictures are mostly genre, sometimes historical, often of children. The theme of many of her pictures is the damsel in distress. A typical example is "Nameless and Friendless" for which there is a preparatory drawing falsely signed Millais in the Ashmolean Museum, Oxford. This picture shows a young female artist trying to sell her work to an art dealer. She is poor, unwed and orphaned as evidenced by her old, worn black clothing. Since she is of a lower class, she cannot sit in the chair by the dealer's desk which would be reserved for artists of a higher status.