Her early debut as an actress came in small off broad way plays like “The Killer inside Me”, “Small Town Gals with Big Problems” and “Urban Planning”. Her initial TV appearance was made in TV shows; The Commish (1991), Due South (1994), Nowhere Man (1995), Misery Loves Company (1995), then came a major breakthrough in her TV career with being casted as Mrs. Smith in the TV series spy show Mr. & Mrs. Smith. Unfortunately the show was cancelled after 8 weeks. Maria landed a role in ER, an American medical drama television series created by novelist and medical doctor Michael Crichton that aired on NBC from September 19, 1994, to April 2, 2009. The show revolved around the inner life of the emergency room (ER) of a fictional County General Hospital in Chicago, Illinois, and various critical issues faced by the room's physicians and staff, Maria guest-starred in it as Dr. Anna Del Amico. The show was a huge success and her impressive work in it drew much attention which led to Bello's movie debut in 1998 film ‘Permanent Midnight’ and successive other movies such as “Coyote Ugly”, “The Cooler”, which bagged her several nominations and awards. In an another film; “A History of Violence”, Bello portrayed a wife under siege from her husband's past, which fetched her a New York Film Critics Circle award and a Golden Globe nomination. In 2009 Bello played the part of the mother of a girl struggling to discover her lost self in the film; “The Private Lives of Pippa Lee”.

The ongoing rush of success didn’t halt there. It continued with a series of other films which paved her way to fame and recognition enabling her to continue her path smoothly.  A handful of high-profile projects had delightfully been added to her resume in 2006, namely; "Thank You for Smoking", "World Trade Center" and "Flicka". The next two years still saw her walk in a steady road with more film titles which included "Shattered" (2007), "The Jane Austen Book Club" (2007), "Downloading Nancy" (2008), and "The Mummy: Tomb of the Dragon Emperor" (2008).

Glancing into her private affairs, the blonde beauty already had a man in her love life, a TV executive named Dan McDermott who became her husband and they had a child together, Jackson Blue, on March 5, 2001.
Maria’s desire of becoming an action heroine was met in the 2008 movie, “Mummy: The Tomb of the Dragon Emperor”. In the same year Bello met a waiter in her family party who became her fiancé.  Reportedly In November 2013, Bello wrote about having a same sex relationship with Clare Munn. She also wrote a book “Whatever....Love is Love”. Her personal interests and ventures make her bio even more gripping. Though following her heart as a thespian, Bello pursued her activism vision, helping to establish the Dream Yard Drama Project for youth in the Bronx and doing vital work for women and families in Darfur and Haiti after the 2010 earthquake. Writing on Bello's activism can be found on her own personal blog as well as on ‘The Huffington Post’. Maria lately starred in a film “The 5th Wave” a science fiction thriller expected to be released in January 2016. Maria’s net worth is estimated to be 96 million USD in 2015.