May left school at thirteen and worked as a barrister's clerk, for an estate agent and as a timekeeper in an iron foundry. He moved from one job to another and ended up begging on the streets. May was a talented artist and he eventually discovered he could make a living by drawing stage celebrities and selling the pictures to theatre fans. This work resulted in the editor of the St. Stephen's Review employing him as a cartoonist.
In 1885 he moved to Australia where he worked for the Sydney Bulletin with Livingstone Hopkins. He returned to London in 1890 and did some book illustrating until he found employment with The Daily Graphic. He was so popular that for twelve years (1892-1904) he published a Phil May Annual. He began contributing cartoons to Punch Magazine in 1893 and two years later became a member of the staff.
Mark Bryant has pointed out that May: "A very fast worker, he used models and was one of the first artists to make full use of the newly invented photographic (as opposed to wood-engraved) method of reproduction. For the Punch drawings he worked first in pencil and then drew over this in pen and ink." Bryant has suggested that "his uncluttered style had immense influence on later artists."
One of those influenced by May was Cyril Bird: "He certainly had a greater effect on pictorial humour... than any other pictorial humorist or his or the following generation, and he showed the way for all the free and lively work which followed after him." David Low admitted in his autobiography that when he was a young man he discovered a pile of old copies of Punch Magazine in a second-hand bookshop in Christchurch. "This... introduced me to the treasure of Charles Keene, Linley Sambourne, Randolph Caldecott and Dana Gibson. The more I poured over the intricate technical quality of these artists the more difficult did drawing appear. How impossible that one could ever become an artist! But then I came on Phil May, who combined quality with apparent facility. Once having discovered Phil May I never let him go."
Although May's cartoons were rarely overtly political, he had a deep sympathy for the poor. Phil May had a unique style. He brought a new simplicity of line to popular cartooning. Not everybody understood his work and one editor asked: "Couldn't you finish up your drawings a bit more?"
Edward Verrall Lucas has argued: "May's line at its best may be said to be alive. It is certain that no English draughtsman has ever attained greater vigour or vivacity in black and white." Percy V. Bradshaw, the author of The Art of the Illustrator (1918) agrees: "He surely gave more magic to a single line than any draughtsman who ever lived, and he was unquestionably the creator of the simplified technique of modern humorous drawing."
Phil May was a heavy drinker. This and his early poverty caused him serious health problems. He suffered from a wasting disease and when he died of cirrhosis of the liver on 5th August, 1903, aged thirty-nine, he weighed only five stone.