The then-10-year-old said in the letter: "It would be my honor to mow the White House lawn for some weekend for you". The letter was publicized by Press Secretary Sarah Huckabee Sanders, and today young Frank got to fulfill his dream.
FX, who lives in the Washington suburb of Falls Church, Virginia, kept on pushing the mower in a long, straight row as Mr Trump walked alongside him.
Frank said he normally charges $8 per lawn, but offered his services to the White House free of charge.
FX's standard fee is $8 per lawn, but he patriotically chose to tackle the White House job free of charge.
The letter made its way to the Oval Office desk and Trump, impressed with the boy's entrepreneurial spirit, obliged the request.
Sanders also announced that Frank was going to be invited to the White House and would get the chance to mow the lawn.
Frank Giaccio spoke to CNN's Alisyn Camerota on "New Day" on Friday before he started work and expressed how excited he is to do the job.
"Maybe he'll be president", Trump said.
President Trump called Frank the 'future of our country'.
While Giaccio mowed the Rose Garden law, the president took the time to stroll along and chat with him. Newsweek reached out to the White House, but no response has been issued.
Frank's offer to work for no charge likely appealed to Trump, who has never been huge on paying his contractors anyway.
On behalf of @FLOTUS Melania & myself, THANK YOU for doing a GREAT job this morning!