He made his acting debut with Vikram Bhatt's horror thriller movie 1920, alongside Adah Sharma, where he played the lead role of Arjun Rathod, who vows to protect his possessed wife. The film was critically and commercially successful in 2008. In 2011, Duggall appeared in next horror thriller Phhir, he collaborated with Vikram Bhatt and Adah Sharma for the second time. He portrayed the role of Kabir Malhotra, a Doctor who is in the search of his wife (played by Roshni Chopra). However, the film met with mixed reviews at the box-office. In 2012, Duggall appeared in Vikram Bhatt's supernatural thriller Dangerous Ishq co-starring Karishma Kapoor and jimmy shergill. The film was the first ever 3D film but could not do wonders at the box-office. In 2014, Duggall played the role of Deepak in Rajshri production's Samrat & Co.and was appreciated in this negative role.

Rajneesh started his career as a Model, by winning the prestigious title of Grasim Mr. India 2003. He also did several TV commercials and ad campaigns like Raymond suitings, Kitkat, Monte Carlo, Wagon R, Yamaha, Videocon, Clinic All Clear.

In 2014, Duggall went on to becoming the winner of the prestigious khatron ke khiladi season 5, for Colors.

Duggall appeared in the blockbuster sensual music video "Mohabbat Barsa Dena Tu" alongside Surveen Chawla, from the Vikram Bhatt's horror movie Creature 3D. In 2015, he played the lead role of Shravan in Bobby Khan's period thriller drama Ek Paheli Leela, co-starring Sunny Leone and Jay Bhanushali. The film met with mixed reviews, and commercially successful at the box-office. He also appeared in Syed Ahmed Afzal's crime thriller Laal Rang as Inspector, multi-starring Randeep Hooda and akshay Oberoi in 2016.

In 2016, Duggall had four solo releases which included Direct Ishq, Beiimaan Love, Saansein and Wajah Tum Ho . Direct Ishq is a benaras based rom-com film which was released on 19 February 2016, starring Rajniesh Duggall, Nidhi Subbaiah and Arjun Bijlani in the pivotal roles. His Dark romantic film Beiimaan Love alongside Sunny Leone saw him playing a flamboyant spoilt brat. He also played the negative lead in Vishal Pandya's multi-starrer erotic crime thriller Wajah Tum Ho alongside sharman josh, Gurmeet Chaudhary and Sana Khan.