Partners at both firms voted over overwhelmingly to merge on Friday 8 December.
The merger will be effective from 1 May 2001, under which Ekelmans' managing partners Jan de Snaijer and Bert Oosting will continue to lead the Dutch practice in the combined firm.
The 13-partner practice covers corporate, finance, IP, projects, property, employment and litigation.
Lateral hires are also on the agenda, particularly in corporate and finance, and other areas of expertise will be added, including a Dutch tax capability.
Ekelmans' corporate client list includes Glaxo Welcome, Merck, Sharpe & Dohme, Honeywell, Rabobank and Holland's third largest bank, Fortis