She began appearing on television at the age of nine playing supporting roles and starring in the comedy-themed show Goin' Bulilit (2012–2015).

Mariano then starred in the television series FPJ's Ang Probinsyano from 2015 to 2016, portraying the role of Rachel Tuazon, the sister of Arjo Atayde's character.

[11] In 2017, Mariano reunited with her Lorenzo's Time co-star Zaijian Jaranilla and paired up together for a Maalaala Mo Kaya episode, Cellphone.

In 2019, she was part of the year's batch of artists launched in the Star Magic Circle together with Kyle Echarri, Melizza Jimenez, Sophie Reyes, Jeremiah Lisbo, Gillian Vicencio, Arielle Roces, Arabella del Rosario, Anthony Jennings, JC Alcantara, Glen Vargas, Kendru Garcia, Eisel Serrano, RA Lewis, Javi Benitez, and Aiyana Waggoner.

[13] In November the same year, it was announced that Mariano will be teaming up with Donny Pangilinan for He's Into Her, an iWantTFC original series directed by Chad Vidanes that is based on the 2013 Wattpad novel of the same name by Maxine Lat a.k.a.

She played the role Trish, hinting the future romance with Dave, Pangilinan's character in the film and previewing her love team partnership with him as DonBelle.

[18] In 2021, the long-awaited series He's Into Her had its record-breaking launch as it crashed the streaming platform iWant TFC upon its release due to the surge of the number of viewers who wanted to watch the premiere episode.

[22] Following the series' success, the cast headlined a special online concert, He's Into Her: The Benison Ball for the fans to enjoy through the streaming platform KTX.ph.

The casts include their He's Into Her co-star Jeremiah Lisbo, as well as singer-actress Angelina Cruz, and TikTok contributor Esnyr Ranollo.

[32] She was also one of the artists to take part in ABS-CBN's 2021 Christmas Station ID, Andito Tayo Para Sa Isa't Isa along with Donny Pangilinan, Martin Nievera, Piolo Pascual, Gary Valenciano, Zsazsa Padilla, Erik Santos, KZ Tandingan, Kathryn Bernardo, Daniel Padilla, Sarah Geronimo, Sharon Cuneta, Vice Ganda, Regine Velasquez, Ogie Alcasid, Iñigo Pascual, Andrea Brillantes, Seth Fedelin, BGYO, and Darren Espanto.

[36] As her first acting project of the year, she starred in the third season of iWant TFC's original anthology series, Click, Like Share for the episode Swap with former Pinoy Big Brother housemate and fellow Rise artist Shanaia Gomez.

The other winners included Yusei Yagi from Japan, Alice Ko from Taiwan, Wallace Chung from China, and Krit Amnuaydechkorn from Thailand.

[45][46] She personally attended the 17th Seoul International Drama Awards that was held on the 22nd at the KBS Hall in Seoul, graced the red carpet event, and shared the stage with K-pop star Kang Daniel, and Japanese actor and singer Yusei Yagi as she received her award and said her acceptance speech.

Mariano won the Listeners’ Choice Award at the inaugural Billboard Philippines Women In Music in March 22.