She usually sang in Hassaniyya, an Arabic dialect spoken mostly in Western Sahara and Mauritania, and occasionally in Spanish.
Her use of the Spanish language was related to the former status of Western Sahara as a Spanish colony.
In early 1976, Hassan joined the musical group Shahid El Hafed Buyema, which, following the death in combat of El-Ouali Mustapha Sayed, first president of the Sahrawi Arab Democratic Republic, became Shahid El Uali.
Hassan travelled with the band to many countries, playing at cultural events and headlining a number of world music festivals.
In 1998, Shadid El Uali disbanded, and Hassan started her solo career with a pair of songs on the album A pesar de las heridas, released by the Spanish label Nubenegra.
For the following concerts in Europe, she was accompanied with the group Leyoad (in which Nayim Alal plays the guitar).
Following the success of their live performances, they recorded in 2000 a collaboration album, Mariem Hassan con Leyoad (in 2002).
In 2004, Hassan contributed to the album Medej, followed by extensive touring in Europe (Barcelona, Madrid, Leipzig, Helsinki, Brussels, Zurich, Antwerp).
Just before departing for her European tour, she received a diagnosis of breast cancer. She began receiving treatment after returning to Spain, staying there on a permanent basis due to the disease.
In 2005, her real first solo album was released. Deseos (Wishes), a personal interpretation of the traditional Haul music.
It doesn’t reveal the tragedies happening during its recording: the death from leukemia of Baba Salama (producer of the album and lead guitarist) before the album was published and Hassan’s struggle with breast cancer.
In March 2005, she was hospitalized in Spain for treatment. One of the highlights of the album is the “desert blues” song “La Tumchu anni”.
Hassan performed at the WOMEX 2005 in Newcastle, and in several editions and locations of WOMAD festival, as WOMAD Las Palmas de Gran Canaria 2008, WOMAD Caceres 2008, WOMAD Charlton Park 2009, WOMAD Sicily 2009, WOMADelaide 2010 and WOMAD New Zealand 2010.
In 2010, a new album was published. Shouka (The Thorn) represented a deep approach to the Haul and even the roots of Azawan music, but also with western influences.
The main song “Shouka” is structured as a cantata, touching all the rhythms of the Sahrawi traditional music, in which Mariem gives a response paragraph by paragraph to the 1976 speech of Felipe González at the Sahrawi refugee camps.
Some critics compared her sound with Tuareg bands like Tinariwen, while others denied similarities.
In March 2011, she performed for three consecutive days in Caracas, Venezuela, during the “Sahrawi Cultural Week”.
Mariem Hassan died of cancer in a Sahrawi refugee camp in Tindouf, Algeria on 22 August 2015, she was aged 56-57