R. K. Laxman was born in Mysore in 1921 in an Iyer family. His Father was a headmaster and Laxman was the youngest of eight children: namely, six sons and two daughters. His elder brother is Novelist R. K. Narayan. Laxman was known as "Pied Piper of Delhi".

Laxman's earliest work was for newspapers Rohan and magazines including Swarajya and Blitz. While still at the Maharaja College of Mysore, he began to illustrate his elder brother R. K. Narayan's stories in The Hindu, and he drew political cartoons for the local newspapers and for the Swatantra. Laxman also drew cartoons for the Kannada humour magazine, Koravanji (which was founded in 1942 by Dr M. Shivaram who had a clinic in the Majestic area of Bangalore. He started this monthly magazine, dedicating it to humorous and satirical articles and cartoons. Shivaram himself was an eminent humourist in Kannada. He encouraged Laxman.)

Laxman held a summer job at the Gemini RohanStudios, Madras. His first full-time job was as a political Cartoonist for The Free Press Journal in Mumbai, where Bal Thackeray was his Cartoonist colleague. In 1951, Laxman joined The Times of India, Mumbai, beginning a career that spanned over fifty years. His "Common Man" character, featured in his pocket cartoons, is portrayed as a witness to the making of democracy. Anthropologist Ritu G. Khanduri notes, "R. K. Laxman structures his cartoon-news through a plot about corruption and a set of characters. This news is visualized and circulates through the recurring figures of the mantri (minister), the Common Man and the trope of modernity symbolized by the airplane (2012: 304)."

Laxman also created a popular mascot for the Asian Paints Ltd group called "Gattu" in 1954. He also wrote a few novels, the first one of which was titled The Hotel Riviera. His cartoons have appeared in Hindi films such as Mr. & Mrs. '55 and a Tamil film Kamaraj. His creations also include the sketches drawn for the television adaptation of Malgudi Days which was written by his elder brother R. K. Narayan, directed by Shankar Nag, and a Konkan coast based Hindi sitcom, Wagle Ki Duniya. Laxman also drew caricatures of David Low, T.S. Eliot, Bertrand Russell, J.B. Priestly and Graham Greene.

In September 2003, Laxman suffered a stroke which left him paralysed on his left side. He recovered from it partially. On the evening of 20 June 2010, Laxman was admitted to Breach Candy Hospital in Mumbai after being transported by an air ambulance from Pune.

In October 2012 Laxman celebrated his 91st birthday in Pune. During a private gathering at his residence, Laxman cut the cake and was presented a DVD of a documentary titled The Brainy Crow by his fan Rajvardhan Patil, depicting the life and survival of the favourite bird of the Cartoonist. Shiv Sena chief Bal Thackeray, who had a past association with Laxman as a Cartoonist, sent birthday greetings to him, family sources said. Scientist Jayant Narlikar and Symbiosis University chancellor S. B. Mujumdar also came to greet him on the occasion.

Laxman died in Deenanath Mangeshkar Hospital in Pune on 26 January 2015 (India's Republic Day) at the age of 93. He was hospitalized on three days earlier for urinary tract infection and chest problems that ultimately led to multiple organ failure. He had reportedly suffered multiple strokes since 2010.