Polychronis Lembesis was born on the island of Salamis, where he spent his childhood, memories of which later influenced his work.

He studied painting initially at The School of Fine Arts, Athens under Nikiforos Lytras and later in 1875 at The Royal Academy of Fine Arts, Munich (with the financial backing of the politician Dimitrios Voulgaris). There he was taught by Wilhelm Lindenscmidt and Ludwig von Lofftz.

While in the Bavarian capital he studied the masterpieces of German Museum collections. In Munich he became a friend of the already well known Greek painter Nicholaos Gysis

In 1880, Lembesis returned to Athens and opened his atelier in the Thission district. Although he was a master in landscape painting he became better known more for his skill in portraiture. He painted portraits of aristocrats and politicians of his age such as Kapsalis, Santarozas, Serpieris, Levides and many others.

Additionally he taught painting to the children of many of his rich clients such as Stephanos Dragoumis, who later became prime minister of Greece. The Dragoumis family supported him for most of his life.

Lembesis died very poor and largely unknown as an artist, perhaps due to a shift in Athenian artistic taste from the Munich School to more modern artistic movements inspired by Paris. In the only obituary written about him, in the Spring of 1913, Pavlos Nirvanas said: ‘An honest and sincere artist has died almost out of tact exactly as he did all his life’.