Plinio Nomellini was born on 6 August 1866 in Livorno, where he was to receive his first artistic education as a draughtsman at the local Scuola di Arti e Mestieri. He moved to Florence in 1885 to attend the Accademia di Belle Arti, then known as the Regio Istituto, after winning a study grant from the Livorno city authorities.
He produced both figure studies and landscapes. Training under Giovanni Fattori, thus in the Italian "Macchiaiolo" school, Nomellini soon fell into line – particularly from 1899 – with the European aesthetic trend, initially drawing close to the studies of the French Impressionists and later to the lively painting of such Neo-Impressionists as Georges Seurat.
His picture Il Fienaiolo (The Hay Gatherer – 1889), which attracted particular praise from his masters and from the Italian critics, was shown at the Exposition Universelle in Paris in that year on the advice of Telemaco Signorini and of Giovanni Boldini.
Devoting his enthusiastic attention to the study of light effects in the 1890s, Nomellini moved to Genoa and began to experiment with the teachings of French Divisionism while at the same time developing an interest in themes of a social nature in the company of his friend Giuseppe Pellizza da Volpedo.
He also befriended other artists and poets such as Ardengo Soffici, Giovanni Pascoli, Dino Campana and Aldo Palazzeschi, or musicians such as Puccini. By the late 1890s he was sensitive to the Symbolist poetic of Odilon Redon and Pierre Puvis de Chavannes and his dreamlike scenarios were to prove a huge success with critics and visitors alike at the 1899 Venice Biennale.
Nomellini also began to work as an illustrator in the early 1890s, cooperating with the Alinari Brothers on an edition of the Divine Comedy and with various different magazines for the publication of poems by his author and writer friends. Barbara Nomellini recalls that from 1907 Plinio, "now a famous painter [...] would paint in the open air on canvases nailed to wooden poles stuck in the sand. These were happy, luminous paintings with his young children Victor, Aurora and Laura breathing life into his enchanted garden, his Eden on earth […]".
From 1908 the garden of his home in Fossa dell'Abate (Viareggio), known by all as "Eden", became a destination of choice for illustrious exponents of Italy's intellectual scene of the day such as Gabriele d'Annunzio, Grazia Deledda, Isadora Duncan, Eleonora Duse and Lorenzo Viani.
Nomellini returned to Florence in 1919 and showed his work at a one-man exhibition comprising fully 43 paintings at the 12th Biennale in 1920. He died in Florence in 1943.
The countless exhibitions at which Nomellini was regularly and expressly invited to show his work included, in particular, the Sezession in Munich in 1901, the International Exhibition in Rome in 1911, the Secessioni Romane exhibitions of 1913 to 1916 and the Rome Quadriennale of 1942.