The services were being held in his home state of Ohio, with the funeral at his former high school and burial at a Cincinnati cemetery.
Sentenced to hard labor for stealing a political poster from a North Korean hotel, the 22-year-old Warmbier was medically evacuated in a coma last week after nearly 18 months in captivity.
Suffering from severe brain damage, he died Monday at a Cincinnati hospital. President Donald Trump slammed Warmbier's detention and eventual death as "a total disgrace."
Speaking early today to assembled reporters across the street from Wyoming High School, US Senator Rob Portman of Ohio highlighted the community support that the Warmbier family has received during the tragedy.
More From This Section
"This process has been a window into both evil, and love and good. Today we're seeing the good, and the love that will be expressed through this outpouring of support for Otto and his family," Portman said.
Like other high-ranking US officials, Portman also criticised North Korea's treatment of Warmbier as "appalling."
Secretary of Defense Jim Mattis said Wednesday that US patience with Pyongyang is running out.
"To see a young man go over there healthy and, (after) a minor act of mischief, come home dead basically... This goes beyond any kind of understanding of law and order, of humanity, of responsibility toward any human being," Mattis said.