Ralph Kiner, a Hall of Fame baseball player who was one of the most prolific home-run sluggers in the 1940s and 1950s and who later became a popular broadcaster for the New York Mets, died Feb. 6 at his home in Rancho Mirage, Calif. He was 91.

The National Baseball Hall of Fame announced his death. The cause was not disclosed.

During a short but spectacular 10-year career, primarily with the Pittsburgh Pirates, Mr. Kiner hit 369 home runs and was named to six All-Star teams.

He topped the National League in home runs every year from 1946 through 1952, becoming the only player in history to lead his league for seven consecutive seasons.

Slow and ungainly in the outfield, the strapping 6-foot-2 Mr. Kiner was a constant threat at the plate. For his career, he averaged one home run every 14 times at bat, the sixth-highest ratio in history, and better than such well-known sluggers as Willie Mays, Hank Aaron, Ted Williams and Mickey Mantle.

Pittsburgh Pirates outfielder Ralph Kiner in 1947, when he led the National League with 51 home runs. (AP)

Mr. Kiner twice belted more than 50 home runs in a season, and his total of 54 in 1949 was not surpassed by another National League hitter until Mark McGwire hit 70 for the St. Louis Cardinals in 1998.

In addition to his seven home-run titles — he was tied with Johnny Mize of the New York Giants in two of those seasons and with Hank Sauer of the Chicago Cubs in a third — Mr. Kiner also had a sharp batting eye and led the league in walks three times. He had at least 100 runs batted in six times and led the league with 127 RBI in 1949.

During his years in Pittsburgh, Mr. Kiner was virtually the only star on a mediocre team. He led the league with a modest 23 home runs as a rookie in 1946.

The next season, Detroit Tigers star Hank Greenberg was traded to the Pirates, and he helped the younger slugger fine-tune his approach to hitting by suggesting that he stand closer to the plate.

“It was like an advanced calculus course,” Mr. Kiner told New York Times in 1997. “It sounds simple, but it was really quite complex.”

The tutelage served him well. On June 1, 1947, Mr. Kiner had only 3 home runs. He then went on a rampage, slugging 48 homers in the remainder of the season to finish with 51.

In 1952, Mr. Kiner led the league in home runs for the seventh time, with 37, but his Pittsburgh team finished in last place with an abysmal record of 42-112. When Mr. Kiner asked general manager Branch Rickey for a pay raise, Rickey reportedly replied, “We finished last with you. We can finish last without you.”

The next year, Mr. Kiner was traded to the Cubs. A nagging back injury forced him to retire in 1955, after a final season with the Cleveland Indians. His career batting average was .279, with a .398 on-base percentage and a .548 slugging average.

In 1962, Mr. Kiner joined the broadcast team of the New York Mets during their first season and remained a mainstay for almost 50 years. He was best known as the avuncular host of his postgame show “Kiner’s Korner,” in which he interviewed players and analyzed the game. He had a rich baritone voice, a keen knowledge of the game and an endless supply of stories. He continued to make occasional appearances in the Mets broadcast booth as recently as last season.

Sometimes known for his malapropisms — “If Casey Stengel were alive today, he’d be spinning in his grave” — Mr. Kiner also spontaneously ad-libbed one of baseball’s most memorable phrases to describe a graceful centerfielder for the Philadelphia Phillies in the 1970s: “Two-thirds of the earth is covered by water. The other third is covered by Garry Maddox.”

Ralph McPherran Kiner was born Oct. 27, 1922, in Santa Rita, N.M. He was 4 when his father died, and he moved with his mother to Alhambra, Calif., near Los Angeles.

He signed a professional baseball contract in 1940, then served as a Navy pilot in the Pacific during World War II. During the offseason, he sometimes dated Hollywood stars, including Janet Leigh, Esther Williams and Elizabeth Taylor.

In 1951, he married tennis player Nancy Chaffee, with whom he had three children. After their divorce in 1968, he married Barbara Ann Batcheldor, with whom he had two more children. Mr. Kiner was married two other times, but a complete list of survivors could not be confirmed.

Mr. Kiner was elected to the Hall of Fame in 1975, the Pirates retired his No. 4 jersey in 1987.

Each year, Mr. Kiner appeared at the Hall of Fame ceremonies in Cooperstown, N.Y., holding court as a grand old man of baseball whose stories never grew old.

“Our style of broadcasting is different from that of the new commentators,” he told the New York Times in 2004. “I prefer the old style of broadcasting in which you talk to the guy sitting next to you as if you were sitting together in the stands.”