Lindsey, who was in declining health since breaking his hip six months ago, died May 4 at his home in Malibu, said his son Trevor.
"Judy at Carnegie Hall," a two-record album, spent 13 weeks at No. 1 on the Billboard chart and won four Grammy Awards, including Album of the Year.
"All you have to do is talk to people who went to that concert, and they will tell you it was the greatest night in show business. It was like a revival meeting," Lindsey told New Jersey's the Record newspaper in 1998.
Garland, he said, "really lived on the stage. I think that's where she was happiest. I was never able to do a concert with her that I didn't get goose bumps, and I did 150 of them with her."
Lindsey also served as music director for "The Judy Garland Show," which aired on CBS from 1963 to 1964.
In 1969, he won an Emmy Award for Outstanding Individual Achievement in Music as musical director for "Barbra Streisand: A Happening in Central Park," a concert videotaped in New York's Central Park's Sheep Meadow, which aired on CBS.
"In a very real way, he was a dream come true for me," Streisand said in a statement to The Times on Wednesday.
"I first saw him when I was a teenager and got to attend a free Judy Garland concert," she recalled. "They were either taping it as a show or for a recording. Mort was on stage conducting for Judy, and I could sense how safe she felt with his judgments and encouragements.
"I stood there fantasizing that one day I would work with him too. And then, that one day arrived and we worked together many wonderful times. He was great."
Lindsey served as musical director for "The Merv Griffin Show" from 1962 to 1986. During his time with Griffin, he was nominated for Emmy Awards in 1970 and '71 for Outstanding Achievement in Music Direction of a Variety, Musical or Dramatic Program.
Lindsey also scored a number of movies, including "40 Pounds of Trouble" (1962), "I Could Go on Singing" (1963; starring Garland), "The Best Man" (1964) and "Real Life" (1979).
Born Mort Lippman on March 21, 1923, in Newark, N.J., he began playing piano as a child. Late at night as a teenager, "he'd sneak out of the house to go down to the jazz clubs and play piano," said his son Trevor, a professional bassist.
"He was a jazz musician probably first and foremost, but he had such an education in formal music that his orchestration skills were pretty much unparalleled," his son said. "He just understood the mechanics of music from schooling, but he was still able to improvise freely on the piano."
Lindsey, who served stateside as a lieutenant in the Army Air Forces during World War II, received a bachelor's degree from Columbia College and a master's from Columbia University in the 1940s. He later returned to Columbia, where he earned a doctorate in music education in 1974.
Lindsey, who was a staff pianist for NBC in New York in the late 1940s, went on to conduct the orchestra on "The Pat Boone-Chevy Showroom" on ABC from 1957-60.
In 1954, he married singer Judy Johnson. Previously known as Betty Bonney, she had a 1941 hit while with Les Brown's band, "Joltin' Joe DiMaggio."
In addition to his wife and son Trevor, Lindsey's survivors include his other sons, David Lippman and Steve Lindsey; his daughters, Bonney Dunn, Deborah Morris and Judy Grant; his sister, Janet; and a number of grandchildren and great-grandchildren.