What is the title of the last major novel Hemingway published in his lifetime?

The last major novel Hemingway published in his lifetime was The Old Man and the Sea. Published in 1952, it is technically a novella, but it is commonly counted among Hemingway's major fictional works and is often described as his last major fictional publication while he was alive.

The story follows Santiago, an aging Cuban fisherman who battles a giant marlin far out at sea. Hemingway wrote it in Cuba between December 1950 and February 1951, completing a manuscript of about 26,500 words. Life magazine published the work in September 1952, followed shortly by the book edition from Scribner's.

The novella became a major literary and commercial success. It won the Pulitzer Prize for Fiction in 1953 and was the only specific work mentioned by the Swedish Academy when Hemingway received the Nobel Prize in Literature in 1954.

A common mix-up is choosing Across the River and into the Trees, published in 1950. That was Hemingway's final conventional novel published during his lifetime; The Old Man and the Sea followed as his final major fictional work.