The appointment of the former French finance minister marks only the latest step in a career notable for history-making moments.
Christine Lagarde was born in Paris and completed most of her studies in France. She graduated from law school at Paris Nanterre University. After being admitted to the Paris Bar, she joined the multinational law firm Baker McKenzie.
Rising through the ranks at her law firm, Lagarde specialized in labor law and anti-trust, as well as mergers and acquisitions.
In 2005, she left Baker McKenzie to jump deep into the world of politics as French minister for foreign trade. Within two years, she was appointed as finance and economy minister of France — becoming the first female chief of finance of a G-7 country.
But her upward trajectory didn't stop there: In 2011, she was nominated managing director of the International Monetary Fund — becoming the first woman to hold that position. She has led the Washington-based institution since then.
Lagarde oversaw bailout programs for Greece, Portugal and Ireland during the sovereign debt crisis that peaked in 2001 and 2012. The three countries use the euro currency as members of the euro zone — meaning she knows the economies she'll soon serve as central bank chief.
Earlier this month, representatives of 28 European countries selected her as the next president of the ECB, where her primary task will be to control inflation and enforce monetary policy decisions for the bloc. She is due to start her new job on November 1.
"I know Christine Lagarde as the boss of the IMF. I know her as a tough lady, as somebody who knows what she wants, who is very clear on giving directions," Mark Rutte, Dutch Prime Minister, told CNBC. "When you come to her to get a loan, (she is) very tough on conditions, so I wouldn't like to be the European country who needs to go to the ECB asking for favors."
While finance minister of France, Lagarde reportedly stepped in to end a 14-year court dispute by ordering a panel of judges to arbitrate a case involving businessman Bernard Tapie — a friend of the French President, Nicolas Sarkozy. The case ended with an order on the French state to repay about 400 million euros in damages to Tapie.
Opponents say Lagarde interfered in the justice system. Supporters argue that the government would have faced a bigger bill if the process had dragged on.
Lagarde's subsequent decision not to appeal the panel's bumper award to Tapie would later see her found guilty of negligence by a court that rules on cases of ministerial misconduct. Lagarde, who could have given up to one-year in prison and a 13,000 euro fine ($14,650), received no punishment.
Lagarde was a member of France's national team for synchronized swimming. She once won a bronze medal in the country's national championships.
European leaders and finance ministers have described Lagarde as the right person to lead the European Central Bank. Her wide contact list and her communication skills are seen as strengths.
Some critics have questioned her ability to take monetary policy decisions, given her background in law rather than economics. However, people familiar with her work at the IMF have said that she is a good listener and is likely to rely on the expertise of the technocrats at the central bank.