Przemysław Wojtaszczyk is interested in fundamental problems of computational mathematics, especially those connected with functional analysis, approximation theory, harmonic analysis and convex geometry. In recent years he actively worked the following areas:

- Wavelet theory;
- Compressed sensing and the general theory of sparse representations;
- Non-linear approximation, in particular greedy algorithms and their use in m-term approximation;
- Mathematics connected with 'reduced basis' method of studying parametric PDE's;
- Geometry of Banach spaces;