CMS Cameron McKenna Nabarro Olswang Pośniak i Bejm is the Polish arm of international firm CMS, which has over 80 offices worldwide. The Warsaw branch was established in 1995 and is led by managing partner, Andrzej Pośniak and supported by a bench of senior practitioners, including Marcin Bejm (energy and infrastructure), Michał Mężykowski (banking and finance) and Jakub Wieczorek (banking and finance).

The firm's strengths lie in project finance as well as power and infrastructure project development, achieving top-tier status in Poland for these practices. The firm also advises on M&A and private equity transactions, particularly in the renewable energy sector.