Family and friends filled the Our Lady of Victory Church in Centerville, Massachusetts, to pay their respects. Hill's funeral was held at 11am a representative for the family, Brian O'Connor, confirmed to USA TODAY.
The Kennedy family has frequented Our Lady of Victory for decades. Former President John F. Kennedy's daughter, Caroline, married Edwin Schlossberg there in 1986, and the church has been the site of a number of funerals and wakes for the extended Kennedy family.
Hill was the only child of Courtney Kennedy Hill, the fifth of Robert and Ethel Kennedy's eleven children.
The cover of the program featured a photo of Hill smiling while on the deck of a boat.
Inside the booklet, next to a picture of her grinning while in the water, was a poem titled "When Saoirse's Eyes Are Smiling."
Family members, including Maria Shriver, her brother Anthony Shriver and her daughter Christina Schwarzenegger were seen at the funeral services, as were Edward M. Kennedy Jr., Joseph P. Kennedy II and his son Rep. Joseph Kennedy III.
Michael O’Keefe, district attorney for Massachusetts' Cape & Islands District, confirmed Hill's death in a statement to USA TODAY on August 1, saying police responded at 3pm to a call about "an unresponsive female, later identified as Saoirse Kennedy Hill."
"Hill was transported to Cape Cod Hospital where she was pronounced deceased," the statement reads. "The cause and manner of death are pending the toxicology report."
The Kennedy family also confirmed her death in a statement to the Associated Press, saying, "Our hearts are shattered by the loss of our beloved Saoirse."
"She lit up our lives with her love, her peals of laughter and her generous spirit," the statement said. "We will love her and miss her forever."
Robert Kennedy’s widow, Ethel, 91, said the "world is a little less beautiful today" following her granddaughter's sudden death.
Speaking to NBC Nightly News on Friday, former Congressman Patrick Kennedy called Hill, his cousin's daughter, "a real hero" in the Kennedy family.
He spoke about how Hill bravely shared her mental health struggles in her high school newspaper three years ago, and praised her for "(opening) the door for her peers to also come out and not feel shamed by this illness."
"We mourn her loss, but her memory will live on as someone who wasn’t going to keep silent and wasn’t going to be feeling as if she had something shameful but rather something medical that she sought treatment for," he said.
Robert F. Kennedy Jr. mourned his niece on Friday, writing on Instagram: "We’ve lost our daughter and our children, their sister. Saoirse was fierce, both in her love for her family and yearning for justice. A fearless adventurer, she inspired curiosity and daring in her friends. But her greatest gift was to find humor in everything and to give us all the gift of her laughter - and our own. The gaping hole that she leaves in our family is a wound too large to ever heal."
Contributing: Joey Garrison, USA TODAY; The Associated Press