Osbert typically employed saints, lambs, and muses to convey his messages in his paintings, which were beautifully executed in blue, silver, violet, and yellow. He would employ pastels and oils to create his beautiful and dreamlike compositions, many of which had an almost misty and ghost-like quality.

His paintings were praised by his fellow Symbolists and were often used as counterparts and illustration for poems by Paul Verlaine and Stephane Mallarme.