T.R. Fatehchand, the producer of Jaal, offered Raj an opportunity to direct his first movie. Milap, an Indian reworking of Frank Capra's 1936 film Mr. Deeds Goes to Town. The screenplay was written by Nabendu Ghosh and starred Dev Anand, Geeta Bali and Johnny Walker. Raj was still learning the ropes and despite the lilting music (N. Datta's debut), the film flopped.

Despite the failure of Milap at the box office, Guru Dutt offered Khosla the opportunity to direct his next production venture, CID. With CID, Raj was much more confident than before. He nailed the musical crime thriller genre he came to be known for. While much of the chases, dark alleys and ominous phone calls were reminiscent of film-noir, CID ended on a hopeful note and had the seeming femme fatale turn over a new leaf. Waheed Rehman made her debut with the film. Raj and she didn't see eye to eye on many aspects. The songs, composed by O.P. Nayyar, were huge hits and remain popular to this day, including the iconic Ye Hai Bombay Meri Jaan and Leke Pehla Pehla Pyar.

With Solva Saal (1958), Raj Khosla had moved out of Guru Dutt's shadow and flying solo. The film was a romantic comedy based on a real-life incident reported in the newspapers. It brought Khosla and Waheeda Rehman back together after CID. S.D. Burman's soundtrack featured the iconic Hai Apna Dil Toh Awaara, sung by Hemant Kumar. Music was becoming a forte of Raj Khosla's directorial oeuvre. He had learned the art of song picturization from his mentor Guru Dutt, a skill that remained with him all his life.

Kala Pani (1958) was an adaptation of A.J. Cronin's Beyond this Place and featured the story of a man striving to clear his father's name. Madhubala and Dev Anand were in their prime, ably supported by Nalini Jaywant. The film contained a depiction of the Other Woman, an element that Raj Khosla would keep going back to, throughout his career. Dev Anand got his first Filmfare Award for his work in the film. The crowning glory of the film was Dev and Madhubala's antics in Achha Ji Main Haari.

Kala Pani was followed by Bombai Ka Babu (1960), Raj Khosla and Dev Anand's last film together. So far, Raj hadn't directed a single film which didn't have Dev at the centre. The story had shades of incest, about a conman (Dev Anand) who pretends to be the brother of a woman (Suchitra Sen) he secretly falls in love with. Though a compelling film, it was seen as too risqué for the time and faltered at the box office. Despite the failure of the film, it was once again a winning soundtrack. Bombai ka Babu was his third consecutive collaboration with S.D. Burman, and the title song has stood the test of time.

For Raj Khosla, the 60s represented the pinnacle of his directorial career. Khosla had a brief spell with Sasadhar Mukherjee and his production house Filmalaya in the early 60s. At Mukherjee's behest, he helmed the film Ek Musafir Ek Hasina, effectively re-launching the pair of Sadhana and Joy Mukherjee, Sasadhar's son. The film also reunited him with O.P. Nayyar as the composer after Milap and CID. Ek Musafir Ek Hasina (1962) was teeming with love ballads.

But the definitive Khosla film from the 60s was Woh Kaun Thi? (1964) the first instalment in a trilogy of mystery films with Sadhana in the lead. While it was partly influenced by Alfred Hitchcock's filmmaking style like close-ups, distinctive camera angles and macguffins, Woh Kaun Thi? contained Raj Khosla's signature filmmaking choices, one of which was showcasing his heroines as goddesses. How he framed Sadhana's face at the beginning of Lag Jaa Gale accentuated allure and mystery while holding on to the romance. It was the beginning of Raj Khosla's stint with Madan Mohan, who continued to compose music for three of his films. Mera Saaya (1966) also makes the romance work while amping up the suspense. Featured pristine Lata Mangeshkar-Madan Mohan ballads like Mera Saaya Saath Hoga, Naino Mein Badra Chhaye, but the one song that ruled the airwaves was Jhumka Gira Re, a song that continues to exist in multiple avatars. Anita (1967), the third part of the Sadhana Trilogy was a failure. Madan and Raj Khosla had a falling out over the theme and Raj had to sign on a pair of young composers billed as Laxmikant-Pyarelal.

Do Badan (1966) was projected as a timeless romance, and was Manoj Kumar's second collaboration with Raj Khosla after Woh Kaun Thi? It was Manoj's idea to repackage the plot of Deedar (1951) to write Do Badan. The title of the film was a nod to an eponymous poem/ song by Makhdoom Mohiuddin Do Badan Pyar Ki Aag Mein Jal Gaye. Manoj was keen to learn filmmaking and reportedly contributed to the script. Do Badan was the only film of Khosla's which had the composer Ravi attached as music director.

For Raj Khosla, the 60s was rounded off with Do Raaste, an ensemble family drama which brought together veterans Balraj Sahni and Kamini Kaushal with relative newbies like Bindu and Prem Chopra. But it famously helped launch the career of a youngster named Rajesh Khanna. Released alongside Aradhana, Do Raaste was also responsible for Khanna becoming an overnight sensation. It brought forth a new romantic pair on screen: Rajesh Khanna and Mumtaz.

Chirag (1969) was a tearjerker that didn't work as well as Khosla had hoped, but it featured strong performances by Sunil Dutt and Asha Parekh. Best remembered for the song Teri Aankhon Ke Siwa Duniya Mein Rakkha Kya Hai. Khosla was enamoured with Faiz Ahmed Faiz's original poem and convinced his lyricist Majrooh Sultanpuri to secure the poet's nod. Chirag was the Khosla's last work with Madan Mohan. Laxmikant Pyarelal became his go-to composers here on out.
Khosla was known for his portrayals of women and his heroines from the 60s were no exception: Sadhana (Woh Kaun Thi, Mera Saaya and Anita), Asha Parekh (Do Badan, Chirag), and Mumtaz (Do Raaste) all had meaty roles and often outshone their male counterparts.

Khosla continued his spate of success with Mera Gaon Mera Desh (1971). Akin to the Western genre of Hollywood, Hindi cinema always had a time-honoured tradition of dacoit aka "daaku" films inspired from the exploits of the notorious bandits of Chambal valley. The plot of Mera Gaon Mera Desh shared some uncanny similarities with Sholay, despite predating the latter by a good four years. It pitted Dharmendra in the lead against Vinod Khanna as the antagonist Jabbar Singh. The film had yet another iconic song from Raj Khosla's stable that became part of cinema folklore, "Maar Diya Jaay Ya Chhod Diya Jaay", which was borrowed by the lyricist Anand Bakshi from the story of Alexander and Porus. By now, Laxmikant-Pyarelal had become his steady composing partners.

Mera Gaon Mera Desh was a blockbuster, but its follow up Kuchhe Dhaage (1973) wasn't as big a success, despite having a credible theme. It examined the futility of revenge and violence among dacoits, and starred Kabir Bedi and Vinod Khanna alongside newcomer Moushumi Chatterjee. Shareef Budmaash (1973) and Prem Kahani (1975) briefly reunited Raj Khosla with Dev Anand and Rajesh Khanna respectively, with limited success. Sunil Dutt, after the debacle of his home production Reshma aur Shera (1971), roped Khosla in for a commercial hit, which he dutifully delivered with Nehle Pe Dehla (1976), which had Raj dabbling in the "lost and found" formula of filmmaking, immensely popular at this time.

But the one film that rounded off the seventies for Raj Khosla and his oeuvre was Main Tulsi Tere Angan Ki. Raj Khosla had a particular fondness for Marathi literature, evidenced in his adaptations of Jayant Deokule's Pathlaag (Mera Saaya) and Chandrakant Kakodkar's Nilambari (Do Raaste). This time, he was adapting Kakodka's novel Ashi Tujhi Preet, with the help of his trusted screenwriter G.R. Kamath. But Main Tulsi Tere Angan Ki also had shades of the turmoil drawing from his own personal life. Both Asha Parekh and Nutan played central roles. Nutan delivered an impeccable performance, one that she herself placed in the league of her work in Sujata and Bandini. The soundtrack by Laxmikant-Pyarelal was well-received, especially the title song and Chhap Tilak Sab Chhini, which was a reworking of Amir Khrusro's eponymous poem. Raj Khosla won his only Filmfare award for the film. The other two wins were for dialogues by Rahi Masoom Raza and for best actress by Nutan.

By the 80s, Raj Khosla was past his prime but there was still one blocksbuster left in him. Dostana had the iconic writer duo of Salim-Javed joining hands with Raj Khosla for the first time. Yash Johar was launching his own production house called Dharma Productions, and it was to be their first venture. It was a sepctacle, starring Amitabh Bachchan, Shatrughan Sinha, Zeenat Aman, Helen, Prem Chopra, Amrish Puri and Pran. Dostana was destined to be Raj Khosla's last big hit, and his only film with Amitabh Bachchan.

Dostana was followed by a string of box office debacles, including titles like Do Premee (1980), Daasi (1981), Teri Maang Sitaron Se Bhar Doon (1982), Maati Maangey Khoon (1984) and Meraa Dost Meraa Dushman (1984). Raj Khosla was roped in to direct the launch vehicles of the sons of his friends Dharmendra and Sunil Dutt. While Sunny (1984) was slated to be Sunny Deol's debut, Betaab (1983) released earlier. As Sunil Dutt was busy tending to his wife Nargis as she was battling with cancer in the US, Raj was tasked with directing several portions of Sanjay Dutt's debut Rocky (1981), including the climax.

Beset with health issues and production bottlenecks, Raj struggled to complete the film that became his swansong, Naqab (1988) starring Rishi Kapoor, Farha, Bindu and Amjad Khan. A Muslim social inspired from elements of Wilkie Collins' The Woman in White and his own film Woh Kaun Thi, the film didn't work at any level but even in his twilight, Raj Khosla delivered a musical masterpiece. He had hired a rank newcomer, Kamal Makhdoom, for the music. The film sank without a trace and so did the music, but Asha Bhosle was so impressed during the recordings that she told Raj Khosla, "This one is going to be my second Umrao Jaan", referring to the eponymous film album which remains one of her classics.
Raj Khosla passed away two years later on 31 May 1991, at the age of 66.