Aiba began his career in the entertainment industry when he joined the Japanese talent agency Johnny & Associates in 1996 at the age of 13.
Prior to his debut as a singer with Arashi in 1999, Aiba started an acting career when he was cast as the lead role of Gordie for the stage play Stand by Me, which was based on the film of the same name.
[1][2] Aiba was raised by his grandparents until he was four years old because his parents were busy running their newly opened Chinese cuisine restaurant then.
[6][7] Aiba began acting in a 1997 stage play based on an American coming of age film called Stand by Me with future bandmates Jun Matsumoto and Kazunari Ninomiya.
[9] In 2007, Aiba portrayed Adam, a shy young man with a heart defect, in Wasurerarenai Hito (忘れられない人, Unforgettable Person).
[10] In early 2008, Aiba was given the lead role of Colin Briggs in the stage play called Greenfingers, which was adapted from the movie of the same name.
[14] In My Girl, Aiba portrayed a young man who discovers that he has a five-year-old daughter after receiving the news that his girlfriend, who he has not seen in six years, was killed in an accident.
[18] Aiba also made a guest appearance on the final episode of bandmate Ninomiya's drama Freeter, Ie o Kau (フリーター、家を買う。, Part-time Worker, Buys a House), which aired on December 21, 2010.
[19] In April 2012, Aiba once again starred in a lead role as "Katayama Yoshitaro" in the NTV drama adaption of the similarly named novel series, " Mikeneko Holmes no Suiri (三毛猫ホームズの推理).
With co-hosts of the show such as Tomomitsu Yamaguchi, Sayaka Aoki and Becky, Aiba interacts with various wild animals such as tigers, pandas and crocodiles in zoos both in and out of Japan, such as Singapore, South Africa, Philippines and Indonesia.
in September, stating as a reason that to continue filming on that stage, with all the memories gathered throughout almost 16 years that the show was on air, would be painfully difficult and heartbreaking.
[30] Aiba, besides hosting the show, has an occasional corner trimming and washing rescued dogs, as part of his desire to take care of animals.
5 Johnny's member alternated hosting the show every night from Mondays to Fridays wherein they try to offer advice as some audience called about their woes.
[34] One of those examples was the family tree of singer and actor Daigo, who found out he was related (by in-law relationships) to John Lennon.
[59] He was once again a navigator on October 18, 2009 for the World Artistic Gymnastics Championships 2009: London Rally (世界体操選手権2009 ロンドン大会, Sekai Taisō Senshuken 2009 Rondon Taikai).
[61] Aiba was the official navigator for Fuji Television's coverage of the 2010 World Artistic Gymnastics Championships, which was held in Rotterdam, Netherlands from October 16 to 24, 2010.
[62] He was chosen, alongside his Arashi co-member Sho Sakurai, to host the NHK special program coverage for the Tokyo Olympics and Paralympics, celebrated from July 23, 2021.
[64][65][66] On October 3, 2021, Aiba served as voice actor for Nissin Foods' subsidiary Koikeya's[67] animated episodes of サスとテナ (Suss to Tena).
The series focuses on sisters Suss and Tena and a tanuki named Bull, who are called to fight monsters caused by environmental and social problems.
Sekai shizen isan) is NHK's 4K channel's 5-episode series, starting March 18, 2023, in which Aiba, as special navigator, hosts a view at Japan's World Natural Heritage.
He also opened the page Aiba Masaki with Callaway Golf on Instagram in which he shares his passion for the game, hoping "to convey its charm to those interested but that have never played, as well as to those who love it".