The deaths were reported by the Syrian Observatory for Human Rights, which said the men were shot, accused by ISIS of gay sex.
Seven of the men, according to the monitoring group,were shot in the town of Rastan, in Homs.
The two other men and the boy were executed in Hreitan.
According to the report, “after accusing [the men and boy] of being homosexual,” and executing them, ISIS destroyed all footage of the killings.
Observatory head Rami Abdel Rahman said all of the cameras used to film the killings were destroyed, despite the executions taking place in public.
According to the Observatory, ISIS has executed at least 3,000 people, including 1,800 civilians.
Two gay men who fled Syria after living under ISIS spoke at the UN to tell of being gay under the regime.
Subhi Nahas and Adnan spoke at a historic meeting of the UN Security Council, which was the first of its kind to address LGBT issues.
There has been a spate of killings by ISIS, of men accused of homosexuality.
Earlier this year, a video, shot in Palmyra, showed two Syrian men be thrown off a building before being stoned to death.
The terrorist group, which operates predominantly across Syria and Iraq, is notorious for filming videos in which captives – usually Westerners or opposing fighters – are brutally slaughtered.
It has also taken to executing men it claims are gay, by throwing them off of tall buildings and pelting them with rocks in IS-produced videos.
Members of the terrorist group, which has published a number of graphic videos featuring the murder of supposed gay men, holds power across parts of Iraq, Syria and Libya.