The star, who passed away aged 89 at his home in Las Vegas on 14 May (15), was remembered by a crowd of 500 at the poignant service in his hometown of Indianola, Mississippi.
Incumbent President Obama and former U.S. leader Clinton both penned special notes which were read out during the service at the Bell Grove Missionary Baptist Church.
Obama wrote, "There's going to be one killer blues session in heaven tonight."
Stevie Wonder also recorded an audio message that was played at the memorial service, telling mourners, "He will forever be the King of the Blues."
Other attendees at the service included King's longterm personal assistant Myron Johnson, who recalled several of his fondest memories of the blues icon, according to The Chicago Tribune.
The mayor of Indianola proclaimed Saturday an official day of remembrance for King, and his body left the church to a choir singing.
He was buried at the nearby B.B. King Museum, where bosses plan to create a memorial garden around his gravesite.
An estimated 4,000 fans turned out to pay their respects on Friday (29May15) when the star's open casket was put on display at the museum ahead of the funeral.