Takeshi Watabe was born on March 21, 1936 in Kochi Prefecture, Japan. His first anime voice acting credits come from 1969, when he provided voices for Ninpu Kamui Gaiden and Under Sea Boy Marine. In the 1970s, the majority of Watabe's voice acting credits are for anime television series. During this decade, he provided voices for The Adventures of Hutch the Honeybee, Ashita no Joe, Devilman, Gatchaman, Kashi no Ki Mokku, Umi no Triton, Kerokko Demetan, Shinzo Ningen Casshan, Maya the Bee, Time Bokan, Gowapper 5 Godam, Lupin III: Part II, Yatterman, Kagaku Ninja-Tai Gatchaman II, The Perrine Story, Cyborg 009, and Kagaku Ninja-Tai Gatchaman F. During this decade, he also provided a voice for the anime film, Hoshi no Orpheus.

In the 1980s, Watabe's voice could be heard in anime series, anime films, and anime OAVs. During this decade, he could be heard providing voices for the following anime television series: Ashita no Joe 2, Densetsu Kyojin Ideon, Maeterlinck's Blue Bird, Galaxy Cyclone Braiger, Sengoku Majin GoShogun, Space Adventure Cobra, Aku Dai-Sakusen Srungle, Armored Trooper Votoms, Genesis Climber Mospeada, Plawres Sanshiro, Fist of the North Star, Aoki Ryusei SPT Layzner, Ginga Nagareboshi Gin, City Hunter, ESPer Mami, Mister Ajikko, Dagon in the Land of Weeds, Little Lord Fauntleroy, Oishinbo, Akuma-kun, and Dragon Warrior. He could also be heard in the following 1980s anime films: Mobile Suit Gundam – The Movie Trilogy, Crusher Joe: The Movie, Ai City, and Fist of the North Star Movie. He also provided voices in these 1980s OAVs: MD Geist, Yotoden, Legend of the Galactic Heroes, Ouke no Monshou, and Riki-Oh.

In the 1990s, Watabe continued providing voices for anime series, anime films, and anime OAVs. During the 1990s, Watabe's voice could be heard on these television series and specials: Dragon Ball Z Special 1: Bardock, the Father of Goku, Karasu Tengu Kabuto, Doraemon, Shin Chan, Yu Yu Hakusho: Ghost Files, Kenyuu Densetsu Yaiba, Ocean Waves, Case Closed, Kaiketsu Zorro, Midori no Makibao, You're Under Arrest, Sailor Moon Sailor Stars, Master of Mosquiton '99, Maze, Pokemon, Cowboy Bebop, Outlaw Star, Princess Nine, Amazing Nurse Nanako, Dai-Guard, Pet Shop of Horrors, and Puppet Master Sakon. He could also be heard in the following anime films: Sword for Truth, Mobile Suit Gundam F91, Mobile Suit Gundam 0083: The Last Blitz of Zeon, Tottoi, Doraemon: Nobita's Adventure in Clockwork City, Doraemon: Nobita Gets Lost in Space, and You're Under Arrest: The Movie. Watabe also provided voices for the following OAVs: Be-Bop-Highschool, City Hunter: Bay City Wars, Condition Green, Mobile Suit Gundam 0083: Stardust Memory, The Super Dimensional Fortress Macross II: Lovers, Again, Black Jack, the second Spirit Warriors OAV, Master of Mosquiton, and Future GPX Cyber Formula Sin.

Watabe continued providing anime voices into the 2000s. During this decade, he could be heard in the following anime series and specials: Najica Blitz Tactics, Noir, Rune Soldier, Salaryman Kintaro, Strawberry Eggs, Aquarian Age – Sign for Evolution, Magical Shopping Arcade Abenobashi, Naruto, Panyo Panyo Di Gi Charat, Pokemon Advance, FireStorm, Full Metal Panic? Fumoffu, Kaleido Star, Requiem From the Darkness, Sonic X, Hi no Tori, The Melody of Oblivion, Paranoia Agent, Samurai Champloo, Gunparade Orchestra, Shinshaku Sengoku Eiyuu Densetsu Sanada Jyuu Yuushi The Animation, Gintama, Kemonozume, Lupin III: Elusiveness of the Fog, Naruto Shippuden, Romeo x Juliet, You're Under Arrest: Full Throttle, Golgo 13, Shigofumi – Letters From the Departed, and Strike Witches. Watabe provided voices for the following anime films: Case Closed: Countdown to Heaven and 6 Angels. He could also be heard in the following OAVs: FLCL, Zone of the Enders: Idolo, Kikaider, New Getter Robo, and Armored Trooper Votoms: Pailsen Files.

Watabe served as a dialect instructor for Ocean Waves. He had roles in such live-action Japanese works as Jinzou Ningen Kikaida, Kamen Rider BLACK, and Kyoryu Sentai Zyuranger. Watabe provided voices for the Japanese video games Langrisser and Hokuto no Ken: Seikmatsu kyuseishu densetsu. He also wrote a book about voice acting titled, Seiyu Naritai.

Sadly, Takeshi Watabe was diagnosed with lung cancer. Watabe passed away on December 13, 2010 at the age of 74 due to pneumonia while undergoing treatment for the lung cancer.