Hengeler Mueller is a globally operating German business law firm. The firm's legal team consists of more than 350 lawyers, including 93 partners, working in offices in Düsseldorf, Frankfurt am Main, Berlin, Munich, Brussels, and London. In addition, the law firm works closely with other European law firms. It has been recognized in the top tier of firms in the fields of mergers & acquisitions, corporate law, capital markets, finance, private equity, structured finance, and dispute resolution.

Hengeler Mueller was established on January 1, 1990, through the merger of the two law firms Hengeler Kurth Wirtz and Mueller Weitzel Weisner. The predecessor firms were a partnership founded in 1947 by Rudolf Mueller in Frankfurt am Main and the law firm of Heinrich Wirtz and Hans Hengeler in Düsseldorf. In the following years, the firms expanded by adding further name partners – Heinz Weitzel and Gerhard Weisner for Mueller Weitzel Weisner and Heinz-Bernd Kurth for Hengeler Kurth Wirtz. Both firms were also active in corporate legal advice, often for representatives of large German banks, insurance companies and industrial corporations.

Following the merger in 1990, Hengeler Mueller established itself as one of the largest domestic business law firms in Germany. In 1998, the firm employed 120 lawyers, including 55 partners, as well as 130 other staff. Later followed an office in London and, in 2006, the opening of the sixth office in Munich. In addition to its existing offices in Düsseldorf and Frankfurt, the firm opened offices in Brussels and Berlin during the 1990s.

The firm was initially structured as a civil law partnership (GbR) and changed its legal form in 2013 to a partnership with limited professional liability (mbB). This change in legal form took place after Hengeler Mueller, together with other business law firms, had been advocating for the creation of the corresponding legal framework since mid-2010.

As of 2025, Hengeler Mueller employs more than 350 lawyers, including 93 partners. The firm follows a lockstep compensation, under which the remuneration of professionals is based solely on the duration of their affiliation with the firm.

Outside of Germany, the firm maintains offices in Brussels and London. In addition, Hengeler Mueller is a member of an international law firm network. This network includes Slaughter and May (United Kingdom), BonelliErede (Italy), Bredin Prat (France), De Brauw Blackstone Westbroek (the Netherlands) and Uría Menéndez (Spain).

As a full-service law firm, Hengeler Mueller covers all areas of business law, in particular transactional work in the fields of mergers and acquisitions, financing and capital markets as well as advice in contentious disputes.

The firm is equally active in the areas of corporate law, banking law, antitrust law, insurance law, tax law, employment law, real estate law, restructuring, compliance and internal investigations, data protection law, competition law, public procurement law, and white-collar criminal law.