Kalki Koechlin was born in Pondicherry, India, on 10 January 1984 to French parents, Joël Koechlin and Françoise Armandie, who came to India from Angers, France. She is a descendant of Maurice Koechlin, a French structural engineer who played an important role in the design and construction of the Eiffel Tower. Koechlin’s parents are devotees of Sri Aurobindo, and she spent a significant amount of her early childhood in Auroville. The family later settled in Kallatty, a village near Ooty in Tamil Nadu, where Koechlin’s father established a business designing hang-gliders and ultralight aircraft.

After facing some early struggle for film roles, Koechlin had four releases in 2011, garnering widespread recognition for her performances in them. The first was Bejoy Nambiar’s Shaitan, a crime-thriller with an ensemble cast that included Koechlin, Rajeev Khandelwal, Gulshan Devaiya, Shiv Panditt, Neil Bhoopalam, and Kirti Kulhari. She played the role of a disturbed teenager and called it an exhausting experience, saying that she felt drained while trying to, “get into a psyche of someone who does a lot of drugs and booze, has lost her mind a little bit and is very vulnerable”. While the character was inconsistently described by film critics as “a nightmare” and “engaging”, Koechlin was praised for her performance, with Raja Sen calling her “an increasingly striking actress”. Upon release the film received positive reviews from critics, and Koechlin was nominated for the Best Actress Award at the Star Screen Awards.

Koechlin married film-maker Anurag Kashyap in April 2011, at her maternal home in Ooty. The two met while filming her debut film Dev.D. On 13 November 2013 Koechlin and Kashyap issued a joint statement addressing their separation. On 19 May 2015, they filed for divorce at a Mumbai family court. During the period between their separation and eventual divorce, the couple went through marriage counselling. Amidst all the news and speculation surrounding the separation, Koechlin revealed that she regretted being so transparent about her personal life, stating in 2012, “It just takes centre stage instead of your work”. Since her divorce, she has rarely mentioned her personal life in public. Tabloids have often linked her romantically with other Bollywood stars, but she has strongly denied any such rumours. Koechlin adopted a rescue cat named Dosa.

Koechlin was the ambassador for Cottonworld’s “Adopt-A-Tree” initiative, under which the brand provided its customers with viable seeds and instructions of planting a tree, urging them to give back to the environment. She endorsed her eco-friendly lifestyle in an interview with journalist Priyadarshini Nandy, ahead of the 2012 Convention on Biological Diversity in Hyderabad. She supported the “Your Cartons. My Classroom” initiative by TERI, Tetra Pak and The Times of India, which promoted the recycling of empty tetra pak cartons into furniture for school classrooms. Koechlin starred in a short film, entitled Hawa Badlo, aimed at spreading awareness on the health concerns of air pollution. She is also a supporter of animal rights, and appeared in a 2012 PETA advertisement campaign encouraging the adoption of stray cats and dogs.

Later in 2013, Koechlin appeared in a video entitled It’s Your Fault, along with VJ Juhi Pandey. Dealing with the issue of sexual assaults on women, the video mocks the mindset that blames women for provoking rapes. It was created by All India Bakchod, and was released on their YouTube channel. It’s Your Fault went viral, with over 150,000 views in two days. Koechlin’s sole release in 2014 was Saif Ali Khan’s Happy Ending, where she plays a comic role of a girl obsessed with Khan’s character. She credited her performance in Yeh Jawani Hai Deewani for landing her the role. She said that people noticed her comic timing in the film, and that worked in her favour. The film, which Koechlin described as “spoof on our film industry and on all the romantic comedies”, opened to mixed reviews and was a box-office failure. Despite the film’s mixed reception she garnered praise for her performance. Saurabh Dwivedi of India Today wrote that “Koechlin steals the show with her perfect portrayal of a nagging girlfriend”, and Rohit Vats of Hindustan Times noted that, although her character in the film felt a bit forced, she delivered a “charming” performance.

Koechlin has been associated with theatre from a young age. As a child, she attended theatre workshops in Pondicherry. Her mother was adamant that she complete her studies before venturing into an acting career, sending her to London to study drama and theatre. During her years in the film industry, Koechlin has continued to participate in theatrical productions. She has written, produced, and acted in several stage plays in India. In a 2014 interview with Verve she said, “Theater is really an actor’s playground […] There’s nothing like performing for a live audience”. Koechlin founded her own theater production company, Little Productions in June 2015.

Koechlin made her directorial debut on stage with the 2015 play Living Room. Development of the play began in 2014, when Koechlin wrote a four-page conversation between Death and an old woman who is in a strange surreal space, about to die but unwilling to exit the world. She further worked on the script of the play in 2015. In a 2016 interview with Mumbai Mirror she said, “Last year, when I was unemployed for six months, I started fleshing out the story. It turned into a comedy on life and death”. The play was staged at the Ranga Shankara Hall, Bangalore, on 24 July 2015. Koechlin also worked in Rajat Kapoor’s What’s Done, Is Done, an adaptation of Shakespeare’s tragedy Macbeth. She played Lady Macbeth and doubled up as one of the witches for the play. The first show of the play was staged on 5 June 2016 in Mumbai.

Koechlin began writing poetry during her childhood and has variously performed and recorded self-written poems. A patron of socially relevant poetry, she performed a solo theatrical monologue entitled, Wo-Manologue at a December 2016 event organised by the FICCI Ladies Organisation. She has also sporadically recited An Intense Piece about the Truths of Womanhood, a soliloquy, on such events as the International Women’s Day special at the India Today Conclave in March 2014 and the 2016 Kalyani Nagar meeting of the FICCI Ladies Organisation. She recited three separate poems focusing on consumerism, the contemporary society, and a comic nursery rhyme at “Spotlight”, a poetry slam in Mumbai. Koechlin was a member of the jury at the 2016 National Youth Poetry Slam, held in Bangalore.

Koechlin appeared alongside Parineeti Chopra, Richa Chadda, and Bhumi Pednekar in Y-Films’s mini web-series Man’s World, a satire on gender roles. The series was released on YouTube in April 2015. She then starred in Anu Menon’s Waiting, an independent film about the relationship between two people who befriend each other in a hospital, while nursing their respective comatose spouses. Koechlin played the role of Tara Deshpande, a young and brash social media-savvy. She dyed her hair black for the role, as Menon wanted her to look more “earthy”. The film had its world premiere at the Dubai International Film Festival (DIFF) in December 2015, and had its theatrical release in India on 27 May 2016. The film and her performance received positive critical reviews. Sukanya Verma of Rediff.com called the film “absolutely riveting”, and also lauded the “stunningly unhindered” Koechlin writing that she used her aura, “in the most mesmeric fashion to create a woman we sympathise with and wish well for”. Film critic Kunal Guha thought that film belonged to Koechlin who, “impresses by managing to wordlessly convey her character’s state of mind in every scene”.

Koechlin advocates for the LGBT rights, and has featured in such video campaigns as Jagatjit Industries’s IICE Vodka advertisement “Kinki Chilli”. Directed by Shiven Surendranath, the video emphasised on an individual’s freedom to choose their sexual identity. Koechlin expressed her support to LGBT community in an International Women’s Day interview with The Huffington Post saying that education was essential for developing sensitisation to LGBT rights. Video messages recorded by Koechlin and Kunal Kapoor, in which they voiced their support for the LGTBQ community were screened at the 2016 Delhi International Queer Theater and Film Festival. Koechlin was featured on the March 2015 cover of Bombay Dost, India’s first gay magazine.

Koechlin is also vociferous on a variety of other issues, including health promotion, education for children in rural areas, and child sexual abuse among others. Koechlin actively participates in the P & G Shiksha campaign for educating children living in rural parts of India. She participated in the 2015 Mumbai Marathon, a charitable event that aimed to spread awareness about issues such as: education, health issues like cancer and AIDS, and senior citizen welfare, accompanied by Shonali Bose’s cousin Malini Chib. Having gone through sexual abuse at the age of nine, Koechlin aims to spread awareness around the issue, saying that it was, “important that parents remove the taboo around the word sex or private parts so kids can speak openly and be saved from potential abuse”. She also spoke at the All Indian Conference for Child Sexual Abuse organised by actor Rahul Bose’s non-governmental organisation HEAL.

Koechlin is a celebrity endorser and has been associated with several brands and services, including: Coca-Cola, Olay, Vogue, Micromax, Titan, Grey Goose’s Style du jour, and AOC International including the cosmetic giant Oriflame. In an interview for Asian News International, Koechlin said that she “believes that everyone, whether an actor or a model, should endorse a brand which matches their ideologies”. She was also the brand ambassador of the “Cinema For Care” section, aimed at creating awareness about disability issues at the All Lights India International Film Festival (ALIIFF) held in Thiruvananthapuram, Kerala in November 2015.

Koechlin starred in a 2016 video, entitled Printing Machine that talked about the approach of media and society towards crimes against women, as a part of Culture Machine’s video series “Unblushed”. The five-minute video was released on YouTube and featured a poem penned and recited by Koechlin. The video was well received by critics and viewers. She also received a letter of appreciation from Melinda Gates, co-founder of Bill & Melinda Gates Foundation, for her contribution to bringing attention to women’s issues. The success of Printing Machine was followed by a second collaborative video for the Unblushed series, Noise, another original poem which was released on the company’s YouTube channel on 22 June 2017 (World Music Day).

Koechlin began working on a podcast for BBC in 2018. Entitled “My Indian Life”, the series had its debut on the streaming networks on 4 August.

Koechlin played a French immigrant in Siddharth Sinha’s short film The Job. Produced by Kushal Shrivastava, the production was a psychological thriller that was meant to be a critique of the corporate sector and its treatment of employees. Her performance attracted praise with writers ascribing the film’s appeal to her persuasive performance. Koechlin was awarded the Order of Arts and Letters by the French government; Alexandre Ziegler, the Ambassador of France to India formally presented the award to her on June, 23. In 2019, Koechlin starred alongside Ranveer Singh and Alia Bhatt in the drama Gully Boy. The film emerged as a critical and commercial success, grossing over ₹2.22 billion (US$31 million) against production budget of ₹400 million (US$5.6 million).

On 30 September 2019, Koechlin confirmed her pregnancy with her boyfriend, Guy Hershberg, an Israeli musician. Their daughter, Sappho was born on 7 February 2020 through water birth.