During the 1970s, she started her career as a comedian with her child role Dagmarita in the comedy series Esto No Tiene Nombre (It does not have name which is an expression in Puerto Rico used when something cannot be explained or it is absurd), broadcast by WAPA-TV.

As the 1980s came about, Dagmar was the host of the variety show Estudio Alegre (Cheerful Studio), in substitution of Awilda Carbia, alongside Juan Manuel Lebrón and Otilio Warrington.

During the month of July 2007, Dagmar, alongside Otilio Warrington, Chucho Avellanet, José Nogueras and Nano Cabrera, starred in Cosa Nuestra (Our Thing), a retrospective of Puerto Rican music and culture during the 1960s, 1970s and 1980s, at the Caguas Performing Arts Center.

On November 10, 2008, her TV producer Antonio (Tony) Mojena and fellow entertainer Raymond Arrieta interrupted their programming to announce that Dagmar would remain away from the cameras for several months while she receives chemotherapy and radiotherapy for a cancerous tumor found at the base of her tongue which does not appear to have metastasized.

[1] She returned fully recovered to the program on May 12, 2009 during a special broadcast attended by many of the nearly thirty entertainers who filled in for her, as well as Governor Luis Fortuño and First Lady Lucé Vela.