At the end of 2023, WSL's 648 employment contracts amounted to 558,1 full-time equivalents (FTEs). Scientists accounted for roughly 58 % of all staff (FTEs). The scientific staff includes 75 doctoral students and 60 post-doctoral researchers. Its staff also included 15 apprentices.

The proportion of women (excluding apprentices) was approximately 38 %. Foreign staff accounted for nearly 35 %. WSL staff came from 41 different countries. German was the mother tongue of most employees (79,3 %).

WSL launched a Visiting Fellows programme to increase research collaboration with foreign scientists. The aim of this programme is to enable leading international researchers at an advanced stage of their career to spend 3-12 months conducting research at WSL. Fellowships are awarded annually to international applicants. Six Visiting Fellows from various research establishments around the world worked at WSL in 2023.