Stars including Beyonce and Stevie Wonder were also in attendance!
Diana Ross knows how to celebrate!
The iconic singer turned 75 on Tuesday and threw both a star-studded birthday party and a special concert in Los Angeles to honor the milestone occasion. After a party at Warwick nightclub -- where she was serenaded with "Happy Birthday" by both Beyonce and Robin Thicke, separately -- Diana jetted down Sunset Boulevard to the Hollywood Palladium for a very special birthday concert, and ET was there!
ET's eyewitness spotted Gayle King entering the venue just after 11 p.m. in a stunning Kelly NG Couture red gown, likely rushing in after having attended the first party. Diana's own entrance was teased on the venue's screen as she was driven there solo in a Rolls-Royce convertible. Upon her arrival at 11:20 p.m., the birthday girl walked straight to the stage from her car via a side door, where she made her grand entrance in a bright orange dress -- her first of five total outfits for the show, all of which were vintage -- while a live band played her 1980 disco song, "I'm Coming Out."
Diddy took the stage next, performing his 1997 hit "Mo Money Mo Problems," which samples Diana's "I'm Coming Out." Diana took it away from there, belting out "Stop! In the Name of Love" (1965), while Diddy's three daughters -- Jessie, 12, D'Lila, 12, and Chance, 13 -- danced. The music icon then ripped off the train on her dress, much to the crowd's delight.
Despite audio issues at the show, the Kardashians in attendance -- Khloe and Kourtney Kardashian along with their mother, Kris Jenner -- all seemed to have a great time and were spotted dancing in the stage side pit to "Come See About Me" (1964) and "You Can't Hurry Love" (1966).
After singing "If We Hold On Together" (1991), which King was seen dancing to on the balcony, Diana changed into a turquoise dress and brought out Stevie Wonder to sing her "Happy Birthday." Thicke was the next guest to take the stage, joining Diana for a rendition of "Endless Love" (1981).
A performance of "Upside Down" (1980) came next, before Diana changed into a red gown to sing "Mirror, Mirror" and tell the crowd that she felt 47, not 75. Next, the birthday girl brought out her son, Evan Ross, and his wife, Ashlee Simpson -- whom Diana referred to as her "daughter" -- and the trio sang the 1976 hit "Love Hangover."
Toward the end of the night, Diana even invited Khloe and Kourtney on stage, where they danced to "Take Me Higher" (1995) before bringing up Diana's kids -- Evan and Tracee Ellis Ross -- and Kris to join them in front of the crowd for "Ease on Down the Road." Kris seemed beyond delighted to be there, grinning as Diana grabbed her hand and escorted her down the stage's runway.
The outfit changes kept coming, with Diana donning a champagne-colored gown before belting out "Your Love" (1993) -- a song for which she requested the lyrics be placed on the teleprompter -- and changing into a white dress before singing "Ain't No Mountain High Enough" (1970).
DJ Khaled continued the incredible show with a mashup of his song "All I Do Is Win" (2010) with Diana's "I Will Survive" (1995).
Stevie, Tracee, Ashlee, Diddy and Robin also jumped on stage to elicit an applause for Diana, before the night's honoree brought out a very reluctant, black hoodie-clad Leonardo DiCaprio up on stage with his mom. The Oscar winner quickly shouted "Happy birthday to the legend, Diana Ross," before running off stage, leaving his mom to receive a hug from Diana. The show-stopping concert wrapped just after 1 a.m.
Even after her epic party and concert, Ross still has a ton to look forward to! Diana Ross: Her Life, Love and Legacy, a concert film featuring never-before-seen footage from her 1983 Central Park concert as well as new material, will hit theaters again for one night only on March 28.
Additionally, Ross will continue her 75th birthday diamond jubilee celebrations with the return of Diamond Diana this summer at Wynn Las Vegas. Ross will present six additional performances at Encore Theater beginning June 5.
Get more on Diana's epic birthday bash and her legacy, below.
Khloe Kardashian Turns Heads With Big Hair and Skimpy Gold Gown at Diana Ross' Birthday Party