She made her acting debut in Gustad's Hindi-English heist film Boom starring Amitabh Bachchan, Gulshan Grover, Jackie Shroff, Madhu Sapre and Padma Lakshmi.

[24] Hindustan Times reported that after Boom's release, Kaif was written off due to her poor Hindi and thick British accent;[25] as a result, filmmakers were hesitant in casting her in their films.

Kaif received a reported salary of ₹7.5 million (US$87,000) for the film, the highest for a female lead at the time in South Indian cinema; Sify attributed this achievement to her looks and figure.

A Sify critic wrote that Kaif was "passably competent in a tailor-made role, giving a mild emotional spin to a couple of scenes" but was overshadowed by her supporting actresses.

[46] Taran Adarsh from Bollywood Hungama found Kaif confident in Humko Deewana Kar Gaye and Namastey London and "a revelation" in the latter, praising her for being convincing in the complex scenes.

[52][53] Kaif's final film of the year was Anees Bazmee's comedy Welcome, alongside Akshay Kumar, Nana Patekar, Mallika Sherawat and Anil Kapoor.

[54] Kaif rejoined Akshay Kumar in Anees Bazmee's action comedy Singh Is Kinng, which earned ₹1.25 billion (US$14 million) worldwide to become her sixth consecutive box-office success.

[57] Her portrayal of a girl forbidden by her father from marrying her poor lover was well received by Sify's Sonia Chopra: "Katrina is wonderful, plays the cello convincingly, and looks ethereal.

Also featuring Kareena Kapoor and Arjun Rampal, the tour began in Amsterdam in June and ended four months later in Dubai's Festival City Arena before an audience of 15,000.

[76] Kaif starred with Ranbir Kapoor in Rajkumar Santoshi's hit comedy, Ajab Prem Ki Ghazab Kahani (2009), as an orphan forced to marry a rich man.

[68] She performed with Akon at the closing ceremony of the 2009 Indian Premier League at the Wanderers Stadium in Johannesburg,[79] In 2010, Kaif appeared in Prakash Jha's political thriller Raajneeti as part of an ensemble cast which included Ranbir Kapoor, Ajay Devgan, Arjun Rampal, Nana Patekar, Manoj Bajpai and Sarah Thompson.

[90][91] Kaif's portrayal was not well received; Renuka Rao of Daily News and Analysis found her "drama queen act" poor but noted that she was exceptional in the item number.

[93] The film narrates the story of three friends on a bachelor trip and features Kaif as Laila, a diving instructor who becomes romantically involved with Roshan's character and inspires him overcome his workaholism.

[98] The romantic comedy Mere Brother Ki Dulhan (2011), produced by Yash Raj Films, starred Kaif alongside Imran Khan and Ali Zafar.

[105] Rachit Gupta of Filmfare attributed the song's success partly to her "infectious energy", noting her "gyrations and belly movements were an onslaught of attraction for the fans".

[107][108] Shubhra Gupta of The Indian Express wrote about her performance: "Katrina is an able, animated foil to Salman, her long legs making her leaps and kicks credible".

[120] The film received ambivalent reviews and Kaif was criticised for taking on an insubstantial part, though Taran Adarsh found her to be "ethereal" and "moving with incredible grace in dance numbers".

[129][130] Abhishek Kapoor's Fitoor is an adaptation of Charles Dickens' Great Expectations in which Kaif played a role based on Estella Havisham along with Tabu and Aditya Roy Kapur.

[132] Suresh Mathew of The Quint observed that the poor critical and commercial reception of Fitoor was particularly significant for Kaif, as unlike her contemporaries at this time, she failed to carry a film on her own, and her performance was panned.

[134] Shubhra Gupta of The Indian Express found Kaif expressionless but praised her and Malhotra's energetic dance number in "Kala Chashma", which amassed over one billion views on YouTube.

The film premiered on the Christmas weekend to strong box office collections, eventually grossing over ₹5.6 billion (US$65 million) worldwide to rank as her highest-grossing release.

[142][143] Rachit Gupta wrote that Kaif compensated for her limited dialogue by convincingly performing the scenes with hand-to-hand combat and gun fights, calling it "invigorating to see a lady kick-ass with so much élan and pull all the punches like they're real".

[150] Calling her one of Bollywood's "scene stealers" in 2018, Sukanya Verma thought Kaif was a "revelation" and her "constantly crying eyes, poker-faced cynicism and wholehearted submission to demeaning impulses underscore the fragility under the furore".

[156] While reviews of the film were varied,[157] Mike McCahil of The Guardian noted the "well-tended chemistry" between Kaif and Khan and thought "the sincerity in her gaze" helped the audience ignore her character's questionable choices.

[165] A reviewer in critic Roger Ebert's website wrote that Kaif "gets to steal a couple of scenes", in particular a combat sequence in a bathhouse, while maintaining a superior allure with a gun compared to her co-star Salman Khan.

[173][174] The Times of India reported in 2009 that she visits Siddhivinayak Temple, Mount Mary Church, and Sufi shrine Ajmer Sharif Dargah before her films are released.

[182] Kaif married actor Vicky Kaushal on 9 December 2021 in a traditional Hindu wedding ceremony at Six Senses Resort, Fort Barwara in Sawai Madhopur, Rajasthan.

[187] In 2019, she launched the #Kare initiatives, a charitable program under her cosmetics' brand Kay Beauty in support of various social causes including employment of rural women.

[11] As part of a career analysis, Nivedita Mishra of Hindustan Times noted that despite her initial poor command of the Hindi language and an unsuccessful acting debut, Kaif later took on roles in films that highlighted her "charming and jovial" screen presence.

[212] Writing for Firstpost, Anuya Jakatdar suggested that Kaif should accept challenging parts instead of "coasting on her co-star's box office appeal" and criticised her inclination towards glamorous roles.