Monge started out by winning a radio contest in 1969. Later on, she made her tv debut on Luis Vigoreaux's show, Luis Vigoreaux Presenta. She had a regular section in that show. In 1970, she signed with record label Patty Records, which released her first album, named Puerto Rico's Poignant...Powerful...Incomparable:Yolandita Monge.
It was her cover of Italian hit Vida that made her an international star after she released her first album. At that young age, Yolandita would perform with legendary Argentinian singer Libertad Lamarque and then sing at the Festival De La Cancion Nueva York (New York Song Festival). Soon, she found another job on tv, this time on Tommy Muniz's show, El Show Del Mediodia.
She followed up with some other hits in Puerto Rico, but then she went to Mexico, where she signed with TECA records and had hits such as Vete de Aqui (Get Out Of Here), Porque Papa? (Why, Dad?) and La Voz Del Silencio (The Voice of Silence).
1975 was a big year for Monge because she released a song named Cierra Los Ojos (Close Your Eyes), which earned her wild fame in such South American countries as Colombia, Chile, Ecuador, Venezuela, Peru and Argentina.
Soon after, she would be signed by Coco Records of New York, and her career kept going on a steady rise internationally. She sang at the prestigious Carnegie Hall, and by 1982, international label CBS International, Julio Iglesias' label, signed her up into their line-up. She then released another album with many top hits and in 1983, she won the prestigious Buga Festival, in Buga, Colombia.
Monge went into a stride in the middle 1980s, when she released what is possibly her greatest album ever: Luz de Luna (Moonlight). This album included her classics Te Veo Pasar (I See You Walk By), Senor Del Pasado (Man From The Past) and El Poder Del Amor, which was a cover of an English hit by the name of The Power of Love (the one that Celine Dion covered in English years later). With that album and CD, she became the first Puerto Rican female singer to earn a golden album during the decade of the 1980s.
She came back with the production of Laberinto de Amor (Labyrinth of Love), which earned her another gold album and later went platinum.
In 1988, she returned to the platinum level with her album Vivencias (Anecdotes). This album included such songs as Acariciame (Caress Me) and Este Amor Que Hay Que Callar (This Love That we Must Keep as a Secret).
After that, she released Portfolio, with the help of famous singer Ricardo Montaner. With Portfolio, she was able to sing at Puerto Rico's Centro de Bellas Artes, and at the Madison Square Garden.
Monge has been nominated for the Grammy in the Latino division, and she was honored in 1996 by the Puerto Rican senate for her long career as a singer. She also earned one of the prestigious Premios Lo Nuestro awards, and she has participated in the annual music videos produced by Banco Popular de Puerto Rico, which usually include only the most important singers the island has to offer. She has also acted in various Spanish soap operas and theatre plays. Among the telenovelas she acted in was La Mentira (The Lie), Poquita Cosa (Small Thing), Escandalo (where she acted alongside Andres Garcia, Iris Chacon and Charytin Goyco), and Ave de Paso (Fly by Bird), where she was the main actress.
Monge has taken a long lay-off from her career after the early 1990s, but she hasn't been afar from controversy. After Pilar Montenegro covered one of her hits, Monge expressed her displeasure at Montenegro singing one of Monge's songs.
But it should be said that although her supposed rivalry with Nazario was well published and talked about on the press and gossip magazines such as Vea, they themselves never confirmed or denied that such a rivalry actually existed.
During June 2003, Yolandita was part of a line of wntenesses in a domestic violence trial with actor and model Osvaldo Rios as defendant. Her testimony was key for the posecution as she had witnessed the aftermath of an encounter on the face of Osvaldo's girlfriend.