In 1962 Paczyński became a member of the Centre of Astronomy of the Polish Academy of Sciences, where he continued to work for nearly 20 years.

[2] In 1981 Paczyński visited the United States, where he gave a series of lectures at Caltech to former interns at his Warsaw-based institute.

[6] His new methods of discovering cosmic objects and measuring their mass by using gravitational lenses gained him international recognition, and he is acknowledged for coining the term microlensing.

In January 2006 he was awarded Henry Norris Russell Lectureship of the American Astronomical Society, "for his highly original contributions to a wide variety of fields including advanced stellar evolution, the nature of gamma ray bursts, accretion in binary systems, gravitational lensing, and cosmology.

His research has been distinguished by its creativity and breadth, as well as the stimulus it has provided to highly productive observational investigations".