In 1990, Rouass married Abdeslam Rouass in Tower Hamlets, London. They divorced in 2003. She went through a religious ceremony in 2005 with Nasir Khan, a businessman, however the two never legally married. In October 2006, Rouass saw a Doctor regarding back pains only to find she was six months pregnant. She and Khan split briefly during the pregnancy and then reconciled. She gave birth to a daughter, Inez, in February 2007. She and Khan separated again in 2008, after which Rouass raised her daughter by herself. In February 2013, she became engaged to professional snooker player Ronnie O'Sullivan, with whom she had been in a relationship since early 2012.

Rouass' first film was City of Dreams produced by Feroze Nadiawala, in which she starred opposite Lisa Ray and Saeed Jaffery. During the years that she was based in India, early in her career, she acted in some Indian films, Aditya Bhattacharya's Indo-Italian Senso unico (1999) and Dev Benegal's Split Wide Open (1999).

In 2000, Rouass starred in Jag Mhundra's controversial film, Bawandar (English title; The Sand Storm), about revenge rapes in Rajasthan, and she made her English-language film debut in 2002 with a small role in The Four Feathers opposite Heath Ledger.

She starred in The Hunt Feast (2004), and in 2006 she was cast in Aditya Raj Kapoor's film Don't Stop Dreaming.

Rouass also appeared in the independent British film Shoot on Sight (2007) opposite Brian Cox, Om Puri and Sadie Frost. In 2008, she appeared in two films, Freebird and the New Zealand funded Apron Strings.

In 2009 she appeared as Egyptologist Sarah Page in the third series of the ITV science-fiction series Primeval. She left the show when location of filming was changed to Dublin, for series four and five, saying it would be hard to continue participating as she was a single parent.

In spring of 2010, Rouass announced that she will be making a film about Leila Khaled, who led the hijacking of a FLIGHT from Rome to Athens in 1969. Rouass stated she had funding for the film.

She played Maya Lahan, a regular character introduced in the ninth series of BBC One drama Spooks which broadcast from September 2010. She guest starred as the evil Colonel Karim in The Sarah Jane Adventures in October 2010. Rouass then joined the cast of the BBC medical drama Holby City, appearing from February 2011 as registrar Sahira Shah. She left Holby City on 17 April 2012, after just 14 months on the show, to take a break to spend time with her family. The door has been left open for her to return.

In August 2017, Rouass was caught up in the Barcelona terrorist attack, writing on Twitter during the incident that she was hiding in a restaurant freezer.