In the film, Rocky Balboa (Stallone) faces stiff competition from Clubber Lang (Mr. T), a powerful new contender, and turns to his old adversary Apollo Creed (Weathers) to help him train.

Rocky III is the first film in the franchise not solely distributed by United Artists, due to the company's merger with Metro-Goldwyn-Mayer (MGM) in 1981.

In 1981, five years after winning the world heavyweight championship against Apollo Creed, Rocky Balboa has had a string of ten successful title defenses and his fame, wealth, and celebrity profile have increased.

Rocky's manager, Mickey Goldmill, worriedly eyes a young and powerful contender rapidly rising through the ranks, James "Clubber" Lang.

While unveiling a statue of himself at the stairway by the Philadelphia Museum of Art, Rocky begins to announce his retirement but is cut short when Lang, now the number-one contender, publicly challenges him.

Despite his promise to Mickey to "live in the gym", Rocky insists on allowing the public to watch him train in a crowded hotel ballroom filled with distractions.

Stopping by Mickey's closed gym, the forlorn Rocky encounters his former rival, Apollo Creed, who witnessed the match as a guest analyst.

At the outset of the match, Rocky sprints from his corner, battering Lang with a level of skill and spirit that no one ever expected.

With Lang rattled and vulnerable, Rocky strikes back with a flurry of punches, culminating in a brutal knockout to reclaim the heavyweight championship.

Dennis James (Price Is Right) and Jim Healy appeared as the commentators for the Rocky–Thunderlips match, while LeRoy Neiman was the guest ring announcer.

Both were about the same height as Sylvester Stallone and had the powerful physique he was looking for, but, according to casting director Rhonda Young, Frazier had a stuttering problem, while Shavers had a high-pitched voice which would have undermined the character's menacing presence.

After looking far and wide (even going to prisons in the hope of finding a suitable antagonist), Rhonda Young stumbled upon a television program on NBC, America's Toughest Bouncer, showcasing a sports competition, and was mesmerized by the winner's physical prowess as well as his charisma.

It turned out that not only was Mr. T a perfect fit, but he also proved tremendously determined to give the best possible performance right from the first screen test, for what would be his breakout role.

[8] In preparation for the film, Stallone claims to have got his body fat percentage down to his all-time low of 2.6% and weighed 155 pounds (70 kg).

The film's consensus reads, "It's noticeably subject to the law of diminishing returns, but Rocky III still has enough brawny spectacle to stand in the ring with the franchise's better entries".

[26] Gene Siskel gave the film two-and-a-half stars out of four and wrote, "Sorry to say this, but there's not anything new in Rocky III, and we sit there wondering why it exists."

"[30][31] Tom Milne of The Monthly Film Bulletin wrote, "Starting off with a replay of our hero's second miraculous return from the dead to win the championship back at the end of Rocky II—itself a virtual repeat from the original Rocky—Rocky III soon demonstrates that it has nothing to offer but more of the same ...

There are fleeting moments, thanks chiefly to a personable performance from Carl Weathers, but the time has surely come for Rocky Balboa to take the final count.

Claiming the statue was not "art" but rather a "movie prop" the city considered various alternative locations and settled upon the front of the Spectrum in South Philadelphia.

[45] The steps leading to the east entrance of the Philadelphia Museum of Art are also known as “The Rocky Steps.”[46] A similar statue is located in Žitište, Serbia.