Marini appeared in a number of independent films starting in the mid-2000s, particularly horror films, including In The Dark (2004), Slaughterhouse Phi: Death Sisters (2006), Darkworld (2006), Blood Legend (2006), Gothic Vampires from Hell (2007) and Munch (2008). She has also experimented with stand-up comedy.
Marini, who had some theater experience in Canada, started performing on stage in the Los Angeles area, and became an active member of The Road Theatre Company. Among her credits with that company in 2007 was "Biblio," a Wayne Peter Liebman one-act play about a girl whose psychological issues invoke a barrage images, including a Marilyn Monroe character portrayed by Marini. Also in 2007, she appeared in "Bitch", a dark comedy by Susan Rubin that played at the Bootleg Theater. Marini portrayed a giddy receptionist who has an affair with one of the main characters, a hedonistic public relations firm partner. In 2008, she appeared in a Road Theatre production of "The Friendly Hour" at the Road Theatre, playing one of a group of South Dakota housewives whose life stories are told over a 73-year period.
Marini appeared in the 2008 horror short film Deader Living Through Chemistry, a horror short film about zombies that appeared on the DVD release of George A. Romero's film Diary of the Dead. In 2009, Marini performed in a 15-week run of "Bram Stoker's Dracula" at the NoHo Theatre in Los Angeles, directed by Ken Sawyer. She portrayed Mina Harker, although on rare occasions she served as an understudy for the Lucy Westenra role. Marini received positive reviews; in a review of one of her Lucy performances, Culture Spot LA Writer Julie Riggott said she "made a convincing transformation from meek innocent to voluptuous vampire". Robert Machray of BlogCritics.org wrote she "should get an award for her bloodcurdling screams".
Marini had a supporting role in the 2009 film Ballistica, and played a Texan art dealer in the film The Back-Up Bride (2010). She appeared in the film Psychosomatika (2010) after Director Jeff Graham, who directed her in Blood Legend, contacted her and asked her to audition for a role. Also in 2010 she appeared in comedy sketches for the E! late night talk show Chelsea Lately, and a commercial for the website Vevo with American Idol runner-up Adam Lambert. Marini filmed a number of television pilots around this time, including ones for the Spike and the Oxygen channels.
Marini returned to the stage in 2011, appearing in the Laurel Ollstein comedy "Esther's Moustache" at the Studio/Stage Theatre in Los Angeles. The play was about a female Artist who draws magazine cartoons of beautiful goddesses, and Marini played Lilith, a sex-obsessed imaginary goddess who appears before the protagonist as her alter ego. She received positive reviews for the performance. LA Weekly Writer Steven Leigh Morris called her a "scene-stealer", and the Los Angeles Times called her "an amusingly empty-headed statuesque siren". Natalia Evdikimova of Culver City News wrote that Marini was "superbly cast" and "hard to ignore", adding: "Mara Marini is everything that a sex-loving goddess should be: bossy, sassy and provocative". In 2011, Marini also appeared in the ABC legal drama series The Whole Truth, and that show's casting Director called her for auditions in several other television roles.
Marini appeared in the 2012 film Sushi Girl, reuniting Marini with Director Kern Saxton, who directed her in Deader Living Through Chemistry. Marini also portrayed Gloria, who she described as a "Marilyn Monroe-type scarlet-wannabe", in the 2013 film Rock and Roll: The Movie. She also has filmed performances for the upcoming films Alongside the Night and King of the Road.
