Lagerfeld was born on 10 September 1933 in Hamburg, to Elisabeth (née Bahlmann) and businessman Otto Lagerfeld. His father owned a company that produced and imported evaporated milk; while his maternal grandfather, Karl Bahlmann, was a local politician for the Catholic Centre Party. His family belonged to the Old Catholic Church. When Lagerfeld’s mother met his father, she was a lingerie saleswoman from Berlin. His parents married in 1930.

Lagerfeld was known to misrepresent his birth year, claiming to be younger than his actual age, and to misrepresent his parents’ background. For example, he claimed that he was born in 1938 to “Elisabeth of Germany” and Otto Ludwig Lagerfeldt from Sweden. These claims have been conclusively proven to be false, as his father was from Hamburg and spent his entire life in Germany, with no Swedish connection. There is also no evidence that his mother Elisabeth Bahlmann, the daughter of a middle-class local politician, called herself “Elisabeth of Germany”. He was known to insist that no one knows his real birth date. In an interview on French television in February 2009, Lagerfeld said that he was “born neither in 1933 nor 1938”.

In 1955, after living in Paris for two years, Lagerfeld entered a coat design competition sponsored by the International Wool Secretariat. He won the coat category and befriended Yves Saint Laurent, who won the dress category, and was soon after hired by Pierre Balmain. He worked as Balmain’s assistant, and later apprentice, for three years.

In 1958, Lagerfeld became the artistic director for Jean Patou. In 1964, he went to Rome to study art history and work for Tiziano but was soon designing freelance for a multitude of brands, including Charles Jourdan, Chloé, Krizia, and Valentino.

In 1967, he was hired by Fendi to modernize their fur line. Lagerfeld’s innovative designs proved groundbreaking, as he introduced the use of mole, rabbit, and squirrel pelts into high fashion. Lagerfeld remained with Fendi until his death.

In 1984, a year after his start at Chanel, Lagerfeld began his own eponymous “Karl Lagerfeld” brand. The brand was established to channel “intellectual sexiness”.

He had an 18-year relationship with the French aristocrat, model, and socialite Jacques de Bascher (1951–1989), though Lagerfeld said that the liaison never became sexual. “I infinitely loved that boy,” Lagerfeld reportedly said of de Bascher, “but I had no physical contact with him. Of course, I was seduced by his physical charm.” De Bascher also had an affair with the couturier Yves Saint-Laurent; subsequently, Saint-Laurent’s business partner and former lover Pierre Berge accused Lagerfeld of being behind a gambit to destabilize the rival fashion house. De Bascher died of AIDS in 1989 while Lagerfeld stayed on a cot at his bedside in his hospital room during the final stages of his illness.

In 1993, US Vogue editor-in-chief Anna Wintour walked out of his Milan Fashion Week runway show, when he employed strippers and adult-film star Moana Pozzi to model his black-and-white collection for Fendi.

Lagerfeld lost 42 kg (93 lb) in 2001. He explained: “I suddenly wanted to dress differently, to wear clothes designed by Hedi Slimane … But these fashions, modeled by very, very slim boys—and not men my age—required me to lose at least 40 kg. It took me exactly 13 months.” The diet was created specially for him by Dr. Jean-Claude Houdret, which led to a book called The Karl Lagerfeld Diet. He promoted it on Larry King Live and other television shows.

In 2002, Lagerfeld asked Renzo Rosso, the founder of Diesel, to collaborate with him on a special denim collection for the Lagerfeld Gallery. The collection, Lagerfeld Gallery by Diesel, was co-designed by Lagerfeld and then developed by Diesel’s creative team, under the supervision of Rosso. It consisted of five pieces that were presented during the designer’s catwalk shows during Paris Fashion Week and then sold in highly limited editions at the Lagerfeld Galleries in Paris and Monaco and at the Diesel Denim Galleries in New York and Tokyo. During the first week of sales in New York, more than 90% of the trousers were sold out, even though prices ranged from $240 to $1,840. In a statement after the show in Paris, Rosso said: “I am honored to have met this fashion icon of our time. Karl represents creativity, tradition and challenge, and the fact that he thought of Diesel for this collaboration is a great gift and acknowledgement of our reputation as the prêt-à-porter of casual wear”.

In December 2006, Lagerfeld announced the launch of a new collection for men and women dubbed K Karl Lagerfeld, which included fitted T-shirts and a wide range of jeans. In September 2010, the Couture Council of The Museum at the Fashion Institute of Technology presented Lagerfeld with an award created for him, The Couture Council Fashion Visionary Award, at a benefit luncheon at Avery Fisher Hall, in New York City. In November 2010, Lagerfeld and Swedish crystal manufacturer Orrefors announced a collaboration to design a crystal art collection. The first collection was launched in spring 2011, called Orrefors by Karl Lagerfeld.

Lagerfeld and investments enterprise Dubai Infinity Holdings (DIH) signed a deal to design limited edition homes on the island of Isla Moda. A feature-length documentary film on the designer, Lagerfeld Confidential, was made by Vogue in 2007. Later in the year, Lagerfeld was made the host of the fictional radio station K109—the studio in the video game Grand Theft Auto IV, Grand Theft Auto IV: The Lost and Damned and Grand Theft Auto: The Ballad of Gay Tony.

Lagerfeld stated in 2007 that his controversial persona was an act.

In 2008, he created a teddy bear in his likeness produced by Steiff in an edition of 2,500 that sold for $1,500. and has been immortalized in many forms, which include pins, shirts, dolls, and more. In 2009, Tra Tutti began selling Karl Lagermouse and Karl Lagerfelt, which are mini-Lagerfelds in the forms of mice and finger puppets, respectively. The same year, he lent his voice to the French animated film, Totally Spies! The Movie.

Lagerfeld was a supporter of the use of fur in fashion, although he himself did not wear fur and hardly ate meat. In a BBC interview in 2009, he claimed that hunters “make a living having learnt nothing else than hunting, killing those beasts who would kill us if they could” and maintained: “In a meat-eating world, wearing leather for shoes and clothes and even handbags, the discussion of fur is childish.” Spokespersons for People for the Ethical Treatment of Animals (PETA) called Lagerfeld “a fashion dinosaur who is as out of step as his furs are out of style”, and “particularly delusional with his kill-or-be-killed mentality. When was the last time a person’s life was threatened by a mink or rabbit?” In 2001, he was the target of a pieing at a fashion premiere at Lincoln Center in New York City. However, the tofu pies hurled by animal rights activists in protest against his use of fur within his collections went astray, instead hitting Calvin Klein. A PETA spokesperson described the hit on Klein as “friendly fire”, calling Klein, who does not use fur, “a great friend to the animals” and Lagerfeld a “designer dinosaur”, who continues to use fur in his collections. In 2010, after Lagerfeld used fake fur in his 2010 Chanel collection, PETA’s website claimed: “It’s the triumph of fake fur … because fake fur changed so much and became so great now that you can hardly see a difference”.

Lagerfeld in 2009 joined critics of supermodel Heidi Klum, following German designer Wolfgang Joop’s remarks about Klum, who had posed naked on the cover of the German edition of GQ magazine. Joop described Klum as being “no runway model. She is simply too heavy and has too big a bust”. Lagerfeld commented that neither he nor Claudia Schiffer knew Klum, as she had never worked in Paris, and that she was insignificant in the world of high fashion, being “more bling bling and glamorous than current fashion”. He created an international furore on 9 February 2012, when he called the singer Adele “a little too fat.” Adele responded that she is like the majority of women, and she is very proud of that fact. Lagerfeld later caused another controversy, on 31 July 2012, when he criticised Pippa Middleton, the sister of Kate Middleton, for her looks.

In April 2013, he finally declared that he was born in 1935. A birth announcement was, however, published by his parents in 1933, and the baptismal register in Hamburg also lists him as born in that year, showing that he was born on 10 September 1933. Bild am Sonntag published his baptismal records in 2008 and interviewed his teacher and a classmate, who both confirmed that he was born in 1933. The same was later confirmed by his death record. Despite that, Karl Lagerfeld announced publicly that he was celebrating his “70th birthday” on 10 September 2008, despite actually turning 75.

In 2013, he directed the short film Once Upon a Time… in the Cité du Cinéma, Saint-Denis, by Luc Besson, featuring Keira Knightley in the role of Coco Chanel and Clotilde Hesme as her aunt Adrienne Chanel. In June 2016, it was announced that Lagerfeld would design the two residential lobbies of the Estates at Acqualina, a residential development in Miami’s Sunny Isles Beach.

Lagerfeld owned a red point Birman cat named Choupette, which, in June 2013, he indicated he would marry, if it were legal.

In 2014, Palm Beach Modern Auctions announced that many of Lagerfeld’s early sketches for the House of Tiziani in Rome would be sold.

In October 2018, Lagerfeld in collaboration with Carpenters Workshop Gallery launched an art collection of functional sculptures titled Architectures. Sculptures were made of Arabescato Fantastico, a rare vibrant white marble with dark gray veins and black Nero Marquina marble with milky veins. Inspired by antiquity and referred to as modern mythology the ensemble consists of gueridons, tables, lamps, consoles, fountains and mirrors.

Following health complications in January 2019, Lagerfeld was admitted to the American Hospital of Paris in Parisian suburb Neuilly-sur-Seine on 18 February. He died there the following morning from complications of pancreatic cancer. Lagerfeld requested no formal funeral with plans for cremation and ashes spread at secret locations alongside his mother as well as his late partner, Jacques de Bascher.

Lagerfeld was memorialized on 20 June 2019 at the Grand Palais with “Karl For Ever”, a celebration of the designer’s life, which featured a career retrospective highlighting his tenures at Chloé, Fendi, and Chanel. The 90-minute tribute was attended by 2,500 guests. Nearly 60 gigantic portraits were on view within the pavilion, which has hosted many Chanel runway collections. The ceremony also included readings and musical performances by Tilda Swinton, Cara Delevingne, Helen Mirren, Pharrell Williams, and Lang Lang. The production was staged by theater and opera director Robert Carsen.

Following the memorial, the house of Karl Lagerfeld announced in July 2019 the development of “The White Shirt Project”. In homage to its eponymous founder, this collaboration celebrates the late designer’s legacy with a collection of reimagined, iconic white shirts.