Yasushi Akimoto, general producer of AKB48, took notice of her popularity and gave her a chance to join AKB48 on the condition that she learn the group's 12 songs and dances in four days.

as the "queen of TV commercials" (CM joō) for 2012 for having more contracts (a total of 20) with companies to appear in their ads than any other female tarento (fellow AKB48 member Tomomi Itano was tied at 20).

[5] On 24 January 2016, Shinoda appeared as the lead actress in Korean rapper Zico's 'It Was Love' music video.

[16] On April 1, 2020, Shinoda's mother announced on her Instagram that Mariko gave birth to a daughter named Mei.

[citation needed] In December 2022, reports were circulating that Shinoda and her husband of three years were separated since August 2022 due to her alleged infidelity, and is fighting over parental rights of their daughter.