At 13, he started writing for the Pennsylvania-based 8mm Collector, with a column called Research Unlimited, where he answered film questions.

[6][7] In the December 1968 issue of Esquire magazine, he wrote an article listing his 75 best movies shown on television and the 25 worst.

An English teacher at Teaneck High School suggested that Maltin meet a friend of hers at publisher New American Library who was looking for someone to edit a film guide and in September 1969, at age 18, Maltin edited his first book, TV Movies, a compendium of synopses and reviews, with the subtitle, "Everything You Want To Know About More than 8,000 Movies Now Being Shown on TV".

In 2005, many films released no later than 1960 were moved into a spin-off volume, Leonard Maltin's Classic Movie Guide, to allow the regular book to cover a larger number of more recent titles.

Starting on May 29, 1982, Maltin was the film reviewer on the syndicated television series Entertainment Tonight for 30 years.

He also spearheaded the creation of the Walt Disney Treasures collectible DVD line in 2001,[16] and continued to provide creative input and host the various sets.

[18][19] In the mid-1990s, Maltin became the president of the Los Angeles Film Critics Association and is on the advisory board of the Hollywood Entertainment Museum.

In 1985, he delivered a three-word movie review on Entertainment Tonight for that year's horror film spoof, Transylvania 6-5000.

This scene echoed real life, as Maltin gave the first film a bad review, finding it mean-spirited, which affected his friendship with director Joe Dante.

Maltin was parodied in the South Park episode "Mecha-Streisand" (1998) where he, Sidney Poitier, and Robert Smith fight a Godzilla-like robot version of Barbra Streisand.

[22] Maltin was one of the few people to appear as a "guest star" on Mystery Science Theater 3000 during its original run; during a Season Nine episode, he joins Pearl Forrester in torturing Mike Nelson and the bots with the film Gorgo.

[25] Comedian Doug Benson's podcast Doug Loves Movies features a segment called the Leonard Maltin Game, in which the guest must guess the name of a film based on a subset of the cast list in reverse order and a few intentionally vague clues from the capsule review of the film from Leonard Maltin's Movie Guide.

It began on Paul Scheer's now-defunct Wolfpop network, with comedian and actor Baron Vaughn as a co-host.

[31] Since 2018, Maltin has served on the advisory board for Legion M.[32] In 2022, he was invited to join the Academy of Motion Pictures Arts and Sciences as part of the Member at Large branch.

[33] Leonard Maltin's Movie Guide has been praised by comedian Patton Oswalt, who described it as "a paperback Kubrickian monolith of one man's massive and far-reaching tastes.

"[36] In the 1995 video release of the original Star Wars trilogy, there was an interview with George Lucas conducted by Maltin before the start of the films.

He is married to researcher and producer Alice Tlusty, and has one daughter, Jessie, who works with him (his production company, JessieFilm, is named for her).

The statement had appeared in print in Maltin's annual movie guide for nearly 25 years before he publicly apologized for the error.