Harrison is believed to have died on Friday following a suspected drug overdose, according to the Harrison family spokesperson Laura Herlovich, reported the Associated Press.
“Our family is extremely saddened by the death of Adam,” a short statement from the family issued by Ms Herlovich said, "We ask for privacy as we grieve his loss.”
Ms Herlovich added that she did not know where Harrison died or what substance he overdosed on.
Rick Harrison posted a picture of them together on Instagram with the caption, “You will always be in my heart! I love you Adam.”
Donald Trump Jr sent his condolences in the comment section, writing, “I’m so sorry man”, and YouTuber Dennis Roady also said, “Sorry to hear about this, wishing Adam, you and your family peace through this moment.”
While Adam did not appear on his father’s hit TV show Pawn Stars, his brother Corey was well-known to fans for appearing alongside Rick as they run the pawn shop on the Las Vegas strip.
Corey also put up a tribute post to his brother, with a childhood picture of them both from 1988, captioning it “I will always love you bubba”.
Rick’s Gold & Silver Pawn Shop became the centre of the History Channel show, which debuted in 2009, yet Harrison did not appear to be seen in any of the aired episodes.
Harrison also had another brother named Jake from his father.
Rick also suffered another loss a few years ago when his father, Richard Harrison, known to Pawn Stars fans as ‘The Old Man’ on the show, died in June 2018 at 77.
Las Vegas Metropolitan Police Department told TMZ that they are investigating Harrison’s death.
The Independent has contacted family spokesperson Laura Herlovich and the Las Vegas Metropolitan PD for comment.