ITV's Our Cilla will celebrate the life of the Liverpudlian singer and entertainer, who died on August 1 at the age of 72.
Famous faces including Elaine Paige, Christopher Biggins and Lynda la Plante will join members of Black's family and her close friends - as well as her costume designer, hairdresser and photographer - to share their insights on the showbiz legend.
The documentary will feature rare interview and archive footage of Black, who rose to fame in the 1960s with hit songs including Anyone Who Had A Heart and You're My World.
She then transformed herself into one of the nation's most famous entertainers as the front woman on shows such as Surprise! Surprise! and Blind Date.
Black became the first woman to have her own prime-time chat show on BBC One, a variety show called Cilla which ran for eight years.
The tribute programme follows ITV's 2013 biopic, The One & Only Cilla Black, which starred Sheridan Smith and told the story of her rise to fame and pulled in more than seven million viewers.
Reading the eulogy at Black's funeral in August, O'Grady said: "I am just so grateful that she allowed me into her whirlwind of a life and we spend nearly two decades together hellraising - if you pardon the expression. I loved her dearly.
"Cilla, I would just like to say, 'thanks for all the fun, thanks for all the laughs - ta-ra girl, I will see you on life's highway'."
Sir Cliff Richard described Black as "the greatest TV presenter of all time" and praised "all the fabulous things about her".
'Our Cilla' airs on Christmas Day at 10.45pm on ITV.