Musicians and dancers were among the mourners, in keeping with the larger-than-life star's request that her funeral be a celebration.
Her coffin, covered in a Lebanese flag, was brought to the Mar Gergis church in the centre of the Lebanese capital for a service presided over by Maronite Patriarch Beshara Rai.
Among the mourners were some of Lebanon's best-known artists and top politicians, but also many ordinary citizens, who both wept and sang.
"She was just the best. We have lost her, but she'll stay in our hearts," said Fatima, dressed in a headscarf and black coat.
"Sabah's death in a loss for all of Lebanon," added Maria, another mourner.
The iconic singer and actress was beloved throughout the Arab world, with her seven-decade career and her colourful love life keeping her in the headlines until the end.
Born Jeanette Gergis Feghali, she later took the screen name Sabah (Morning in Arabic), but was affectionately known by the diminutive Sabbuha, or the nickname Shahrura (songbird).
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She began performing in the 1940s, earning a reputation for her renditions of patriotic songs as well as folkloric ballads.
She was also an icon of the big screen, appearing in more than 90 movies.
But it was her light-hearted style and her willingness to challenge social conventions, with daring outfits and bold pronouncements, that endeared her to fans and kept her in the public eye.
She is believed to have tied the knot at least nine times, and shocked fans well into her later years, getting engaged briefly in 2003 to a "Mr. Lebanon" winner several decades her junior.
Sabah kept up the glamorous style of her youth even as she aged, keeping her hair long and platinum blonde and undergoing multiple plastic surgeries.
Though in later years she was sometimes the butt of jokes about her longevity and quest for youth, she remained a national icon in Lebanon and beyond.
Her funeral was covered live by almost every domestic Lebanese television station, though the Al-Manar channel of the conservative Shiite movement Hezbollah ran its regular programmes.
As her coffin was brought out of the church after the service, mourners showered it with flowers, some waving the Lebanese flag as they cheered.
Among those in attendance was Fadi Lebnan, who was married to Sabah for 17 years -- her longest union.
"Sabah was a one-off, she can never be repeated," he told AFP. "She is a legend... she was my sweetheart."