Johan is widely respected as a highly skilled European competition lawyer, advising on complex competition issues, including on merger control, anti-cartel enforcement, monopolisation cases and other conduct investigations. He acts as co-head of the firm's Global Competition group and as managing partner of the Brussels office.

Clients turn to Johan when they need cutting-edge competition and regulatory advice. He has been advising some of the world's leading companies for over 30 years on their most complex competition issues. Johan is "an exceptional lawyer who is solution-oriented, has a remarkable ability to rapidly understand our business and has excellent reactivity" (Chambers Global).  Johan "attracts considerable praise for his reliable practice, as well as his great energy and insight into cartel proceedings" (Who's Who Legal). “Johan Ysewyn has a unique understanding of the EC and a very helpful network of connections across Brussels. (…) One of the best European competition lawyers” (Legal 500).

Johan represents clients from around the world in dealings with competition authorities as well as in court litigation. He has in-depth knowledge of regulatory procedures and best practices as well as longstanding relationships with key regulators, in particular at the European Commission. He has also an active advisory practice covering a range of areas of interest to corporates, including the interplay between ESG goals and competition law, the impact of competition law enforcement on digital markets and broad strategic compliance issues.

Johan’s experience spans many industry sectors, with recent experience in telecoms and information technology, media, healthcare, consumer goods, retail, energy and transport. He has advised on several of the most major merger investigations in recent years. In addition, he has represented clients in many conduct investigations.

Johan’s practice also has a strong focus on global and European cartel investigations. He has acted for the immunity applicants in the bitumen and marine hose cartels, and acted for defendants in alleged cartels in financial services, consumer goods, pharmaceuticals, chemicals, consumer electronics and price benchmarking in the oil sector. He has acted for the European Payments Council in the first European Commission investigation into standardisation agreements in the e-payments sector. Johan has written and lectured extensively on international cartel and leniency-related issues. He co-authors the loose-leaf European Cartel Digest and lectures on cartel law and economics at the Brussels School of Competition.

Johan is also one of the leading experts on EU State aid issues, working both for beneficiaries and governments. He has advised a number of leading banks and governments, as well as represented major European airlines. From the cases that can be publicly disclosed, he has been involved in the Fortis, KBC, Dexia, Arco, Citadele, airBaltic and Riga Airport State aid cases.