Jeanette Anna MacDonald was born in Philadelphia, Pennsylvania to Daniel McDonald (a Scottish American) and Anna May Wright, who was of Welsh, English and Dutch descent. MacDonald made her professional debut at the age of six, singing "Old Mother Hubbard" in a charity opera at Philadelphia's Academy of Music. At the age of 16, accompanied by her father, she went to see her older sister, Blossom Rock, perform on Broadway in New York. An audition was arranged by her sister for a part as dancer in the chorus of another production. Jeanette got the part and was given permission by her parents to take the job. Of her start in Broadway, many years later she told Ed Sullivan, "I got a crick in my neck and $40 a week".

Jeanette MacDonald performed on Broadway a further nine years, progressing to leading roles in Yes, Yes, Yvette (1927), Sunny Days (1928), Angela (1928) and Boom Boom (1929) (opposite a young Cary Grant), before she was chosen by the Hollywood director Ernst Lubitsch to play the lead in his new film musical The Love Parade in 1929.

It was not until Irving Thalberg lured her to Metro Goldwyn Mayer in 1934, that she had her biggest hits including The Merry Widow (1934) (with Maurice Chevalier), Naughty Marietta, Rose-Marie, and Maytime (1937) (all with Nelson Eddy). The latter, where she ages from a young girl to an old woman, is said to have been her favorite role. On very rare occasions she was given roles that allowed to extend her range as a dramatic actress, however she was still expected to sing.

Cast opposite Clark Gable and Spencer Tracy in San Francisco (1936), she was given some key dramatic scenes, but also contributed several obligatory musical numbers.

She did not confine herself to operetta, appearing in stage productions of grand opera, including Charles Gounod's Faust in 1943 and 1951, the latter being her last full length opera performance.

In 1937, Jeanette MacDonald married actor Gene Raymond, who was rumored to be bisexual, with whom she later co-starred in 1941's Smilin' Through. Although they were married until her death from heart disease at the age of 61 in 1965, they had no children. Jeanette continued to work with Nelson Eddy in radio during the 1940s, and in the 1950s they made joint TV appearances and cut a gold record, "Favorites in Hi-Fi (and Stereo)".

Several movies were proposed for the team in later years, including projects written by Nelson, and Florence L. Barclay's classic novel The Rosary, but none got off the ground. Jeanette died in Houston, Texas of heart disease, and was interred in the Forest Lawn Memorial Park Cemetery in Glendale, California.

After her death, rumors began to emerge that Jeanette MacDonald had an off-screen relationship with Nelson Eddy. A biography authorized by Jeanette's widower Gene Raymond, Hollywood Diva by Edward Baron Turk (2000), (ISBN 0520222539), denies there was any such affair.

However, Sharon Rich, a close friend of MacDonald's older sister, TV actress Blossom Rock (from The Addams Family), has written several books supporting these rumors with excerpts from letters, diaries and interviews. Sweethearts by Sharon Rich (revised edition, 2001 - ISBN 0971199817), discusses MacDonald's ill-fated affair with Eddy.

Jeanette MacDonald: The Irving Stone Letters annotated by Sharon Rich 2002, (ISBN 0971199841), is a compilation of Jeanette's handwritten letters to a beau from her Broadway years (with whom she also discusses her Hollywood years), while Jeanette MacDonald Autobiography: The Lost Manuscript annotated by Sharon Rich 2004, (ISBN 0971199884) presents MacDonald's unpublished autobiography, in which MacDonald verifies a problematic marriage.

In answer to unsourced gossip that MacDonald and Eddy could not have had an affair due to Eddy's being gay, Sweethearts quotes testimony of several women who had lengthy heterosexual affairs with him from the 1920s through the 1960s, including Maryon Murphy, wife of film director Ralph Murphy, and author K.T. Ernshaw ("To Love Again") (2001, ISBN 0595166075) who also provided a detailed and candid interview about herself and Eddy, and the Eddy and MacDonald affair, in Mac/Eddy Today Issue #62 and #63" (2003, ISSN 0891-527X).

Another false rumor is that studio head Louis B. Mayer forced Eddy to marry. Eddy's elopement to Las Vegas with Ann Franklin followed MacDonald's well-documented (ie, newspaper blurbs, a photo with Hedda Hopper at her bedside) hospital stays following a miscarriage, her going to Reno to establish residency there so she could obtain a divorce from Gene Raymond, then backing out due to pressure from Mayer.

On the rebound, Eddy eloped with Franklin. Sweethearts cites several sources that Eddy was drunk when he married Franklin; one of the sources was Eddy's accompanist, Theodore Paxson. It should be noted that Gene Raymond, who was also blond and somewhat resembled Eddy, was arrested at least three times for gay-related incidents; a photo of his 1938 arrest and booking number is reproduced in Sweethearts, page 498 of the 2001 edition, an army nurse is named and quoted for the second arrest, while retired Scotland Yard detective Joe Sampson discussed the third arrest,which occurred in England during WWII.

Jeanette MacDonald was given two stars on the Hollywood Walk of Fame for her contributions to Recordings and Motion Pictures.