Both praised Philip’s lifetime of service to the United Kingdom and to his wife, Queen Elizabeth II. William said his grandfather would want the royal family to "get on with the job."
Harry remembered Philip as "my grandpa: master of the barbecue, legend of banter, and cheeky right ‘til the end."
Philip died Friday just months shy of his 100th birthday.
"My grandfather’s century of life was defined by service — to his country and Commonwealth, to his wife and queen, and to our family," William said.
William, who is second in line to the British throne, also said that he will always be grateful that his wife, Kate, had so many years to get to know his grandfather.
In a statement released half an hour later, Harry also reminisced about their grandfather, saying he was "authentically himself, with a seriously sharp wit, and could hold the attention of any room due to his charm— and also because you never knew what he might say next."
Philip was known for speaking his mind and making occasional controversial comments, some of which have been deemed racist or insensitive.
"Meghan, Archie, and I (as well as your future great-granddaughter) will always hold a special place for you in our hearts," added Harry, who is reportedly in the U.K.
Download the NBC News app for breaking news and politics
Harry's return to Britain will be closely watched after he and his wife's interview with the media mogul Oprah Winfrey, which sparked the biggest crisis in decades for the British monarchy.
Their comments exposed a raft of allegations about their lives before and after they split with the royal family, prompting accusations of racism within the royal family. After the interview, William publicly denied the royal family was racist.
Harry and Meghan moved to the United States after stepping back from royal duties last year.
Meghan, who is pregnant with the couple's second child, will not be attending Philip's funeral, scheduled for Saturday, after her physician advised her not to travel, according to Buckingham Palace officials.
Rumors of a rift between Harry and William surfaced in the summer of 2019. In June that year, Harry and Meghan confirmed that they were separating from William and Kate's Royal Foundation charity to start their own initiative, Sussex Royal.
In last month's interview with Winfrey, Harry said his relationship with his brother was "space" at the moment, but he hoped that "time heals all things."
Former British Prime Minister John Major said Sunday that Philip’s funeral and shared grief was an “ideal opportunity” to mend any rifts that may exist between the royal family and Harry.