He has short black hair and blue eyes. He usually wears a black turtleneck tucked in his indigo pants pulled up to his waist by a bright light brown belt with a silver buckle, along with a green jacket, white socks, and dark brown and white shoes.

As Tuxedo Mask, Mamoru wears a formal black tuxedo suit alongside golden buttons and a black cape with a red interior. He also wears a white mask, a formal black top hat, and white gloves. He also wields a black cane and the red rose that he throws on his enemies. Every time when he shields Sailor Moon from an enemy's attack, both his hat and his mask were knocked off to show his true identity.

Mamoru carries the red rose when he transforms into Tuxedo Mask as explained below and upon meeting with the Outer Senshi in Sailor Moon S.

Mamoru is very protective of those he cares about, risking his life to save them. He has likely suffered from loneliness and depression his entire life, and has trauma from the death of his parents resulting in memory loss he seemed to be very cold-natured initially and lacked many friends. He can also be blunt, which has led to him sometimes upsetting those around him due to his harsh words.