Nobuhiro Aihara was born in Isegahara, Kanagawa Prefecture during World War II. Instead of taking over his family's business as was expected of him, Aihara left home to pursue a career in commercial animation and graphic design.

Aihara's career began in the mid-1960s, when he worked at Studio Zero. During his time with Studio Zero, he worked on such series as 1965's Obake no Q-taro and 1968's Kaibutsu-kun. In the 1970s and 1980s, Aihara was a freelance animator and inbetweener. During those years, he did a lot of work with Mushi Pro and Oh! Pro. He has provided work on such anime as Isao Takahata's 1982 film, Gauche the Cellist, Night on the Galactic Railroad, the 1988 Akira film, 1966's Osomatsu-kun, and 1969's Moomin.

In the 1960s, Aihara also worked at making a name for himself as an experimental animator. He had a one-man animation show, and he traveled from Tokyo to Sweden, Denmark, France, Germany, and the Czech Republic. His works included the anime shorts "Ame," "Stop," "Time to Kill," "Sakura," "Fushoku," "Yamakagashi," "Oshihiori Hane," "Akai Gyaman," "Mitsubachi no kisetsu wa satte," "Urushi," "Aisanka Hana," "Shoshun Kitsune-iro," "Tankyori Runner," "Bodo," "Stone," "Stone No. 1," "Kumo no ito," "Light," "Aoi Matchi," "Ringo to Shojo," "Karuma," "Hikari," "Burnin," "Shelter," "Suiwa: Karuma 2," "My Shelter," "Balva," "S=13," "Ouma ga toki," "Private," "Eizo (Kage)," "Tombo," "Gavora," "Line," "Mask," "Karasu," "Spin," "Kido," "Miminari," "Rain," "Memory of Cloud," "Yellow Fish," "The Third Eye," "Wind," "Memory of Red," "Yellow Night," "Yellow Snake," "Black Fish" (for Tokyo Loop), "Lotus," and "Zap Cat." "Stone" was also chosen by the Laputa 150 committee as one of the "30 treasures of world animation" that did not receive recognition in the original poll.

Aihara also collaborated with Keiichi Tanaami on the following shorts: "Yami no Kokyu - Yume no Inei," "Fu no Kokyu," "Scrap Diary," "Running Man," "Fetish Doll," "Landscape," "Yume 10-ya," "Trip," "Madonna no Yuwaku," "Noise," "Issun Boshi (Inch-High Samurai)," "Chirico," "Paradise for Eye," "Shunga," and "Dreams."

Aihara has served as a judge for the Hiroshima and Seoul International Animation Festivals. He also taught as a film professor at the Kyoto University of Art and Design.

Sadly, Nobuhiro Aihara passed away on April 30, 2011 at the age of 66 while on a trip at a hotel in Denpasar on Bali, Indonesia. He was found by a fellow traveler at the hotel, and the authorities determined that Aihara passed away due to natural causes.