Ileana was born in Mumbai, Maharashtra as the second child to her parents Ronaldo and Samira. She has three siblings – older sister Farrah, younger brother Rhys and youngest sister Eileen. Her first name comes from Greek mythology. While growing up, she lived in Goa for about seven years.
During that time, the manager of the hotel her mother was working in, suggested that she should start modelling and fixed a meeting with Marc Robinson. Though initially reluctant, she was persuaded and her first portfolio was created in January 2003, which she described as a "disaster". She began gaining notice through photo shoots and ramp shows and her second portfolio was set up the following year, which landed her three advertisements from Electrolux, Emami Talc and Fair and Lovely. The latter, in particular, which was directed by Rakesh Roshan, gave her exposure and brought in several offers for acting in feature films.
In 2005, Ileana was called for an audition by director Teja, but the project was cancelled. She instead made her feature film debut in the Telugu language romance film Devadasu (2006), directed by Y. V. S. Chowdhary. She underwent acting classes with Aruna Bhikshu, before starting to work on the film. She recalls that during filming she felt "pressured almost cried and didn't want to go further", but went ahead after her mother encouraged her, giving her "the lecture of a lifetime at 3 am." Upon release, critics were in praise of Ileana, particularly referring to her physique and looks; Jeevi of Idlebrain wrote that Ileana "makes a cool debut. She is good at histrionics and has a fabulous body any woman would love to possess. She has great legs and nice physique", while a review from Indiaglitz noted that she "has chiseled features and a figure to die-for." Devadasu, which also marked its lead actor Ram's acting debut, became the year's first major commercial success, eventually grossing around Indian Rupee symbol.svg 14 crores, whilst earning Ileana the Filmfare Award for Best Female Debutant. She next appeared opposite Mahesh Babu in the action flick Pokiri in which she portrayed an aerobics teacher, who is harassed by a corrupt police officer. The film was a huge financial success, emerging the highest-grossing Telugu film of all time until then, as well as Ileana's biggest commercial success so far.
D'Cruz's career took a turn for the better with the release of her well-received 2007 film Aata, acting opposite Siddharth. She received favorable reviews for her performance as Satya, a college student who is on the run from the home minister's crooked son by whom she is targeted, when leading a protest and demanding punishment for his crimes. Idlebrain described her as "gorgeous" and a "treat to watch to the eyes". In 2008, she performed a lead role opposite Pawan Kalyan in Jalsa, directed by Trivikram Srinivas. In spite of opening to mixed reviews, the film turned out to become a high financial success. Ileana received largely positive remarks, with critics citing that she looked "pretty", "damn cool", and "every bit chic and stunning through out the film", while being later awarded the Santosham Award, one of five awards for Jalsa and the South Scope Style Award, besides garnering a nomination for the Best Actress prize at the 56th Filmfare Awards South. Her first 2009 release, titled Kick, was likewise declared a box office success, becoming one of the highest-grossing films that year. Later that year she starred in the films Rechipo and Y. V. S. Choudary's Saleem alongside Vishnu Manchu, both of which performed poorly at the box office. Huduga Hudugi, her first Kannada film, became her only 2010 release; she performed an item number, "Ileana Ileana", in the film.
Apart from movies Ileana is passionate about horses. She has mastered the art of horse riding.
2006 Devadasu Bhanumathi Katamraju Telugu Winner, Filmfare Best Female Debut (South)
2006 Pokiri Shruti Telugu
2006 Kedi Aarthi Tamil
2006 Khatarnak Nakshatra Telugu
2006 Rakhi Tripura Telugu
2007 Munna Nidhi Telugu
2007 Aata Sathya Telugu
2008 Jalsa Bhagyamathi Telugu Winner, Santosham Best Actress Award
Nominated, Filmfare Best Telugu Actress Award
2008 Bhale Dongalu Jyothi Telugu
2009 Kick Naina Telugu Nominated, Filmfare Best Telugu Actress Award
2009 Rechipo Krishna Veni Telugu
2009 Saleem Satyavathi Telugu
2010 Huduga Hudugi Herself Kannada Special appearance
2011 Shakti Aishwarya Mahadevaraya Telugu
2011 Nenu Naa Rakshasi Meenakshi Telugu
2011 Nanban Tamil Filming
2011 Barfee Hindi Filming
2012 Once Upon a Time in Mumbaai 2 Hindi Filming