Mari Uchiyama is a Japanese voice actress from Nara Prefecture, born on July 6th. She is affiliated with the talent agency 81 Produce, which she joined on April 1, 2015, marking the official start of her professional career in the mid-2010s.

Uchiyama is recognized for her versatile vocal range, capable of portraying a wide variety of characters, including passionate young girls, mischievous boys, and fantastical beings. Her fluency in the Kansai dialect, her native regional dialect, adds a layer of authenticity and distinctiveness to her performances.

In television animation, one of her notable roles includes voicing the twin characters April Atwood and May Atwood in the second season of The Ancient Magus' Bride. Her other prominent anime roles include Keiko Ushiroda in Komi Can't Communicate, Makiko Maki in Yu-Gi-Oh! Go Rush!!, and the character Murasaki in Chiikawa. She has also contributed to a wide range of other popular series in various supporting and recurring roles, such as Spy x Family, Ya Boy Kongming!, Blue Lock, and 22/7.

Beyond television, Uchiyama's voice work extends to original video animations, net animations, and theatrical films. Her film credits include Fate/Grand Order: Final Singularity – Grand Temple of Time: Solomon and the Laid-Back Camp Movie. She is also highly active in the video game industry, with significant roles such as Yotsuba Oshima in Heaven Burns Red, characters in Monster Strike, Listil in Langrisser Mobile, and a young Karim in Disney Twisted Wonderland. Her work includes dubbing for foreign films and series, providing the Japanese voice for roles like Rowena in Christmas Again, Margot Kim in Searching, and Rebecca in Thomas & Friends.

Uchiyama has also participated in audio dramas and audiobooks, and has performed character songs for anime projects like Chiikawa and Akroglam. Her hobbies include drawing illustrations and practicing gymnastics moves such as hand springs.