He was accompanied at the Saturday jubilation by Secretary of State Rex Tillerson and Secretary of Commerce Wilbur Ross.
Trump arrived in the Saudi capital earlier in the day on the first leg of a nine-day overseas tour. Upon arrival and official reception, he proceeded to sign the $110-billion deal and other agreements amounting to $250 billion before joining the party.
Saudi Foreign Minister Adel al-Jubeir put the volume of the collective bilateral deals higher, saying they were worth more than $380 billion.
White House spokesman Sean Spicer said on Twitter that the "defense agreement” was the "largest single arms deal in US history."
Speaking after the signing ceremony, Trump said, "That was a tremendous day. Tremendous investments in the United States. Hundreds of billions of dollars of investments into the United States and jobs, jobs, jobs."