In nphp1KO MDCK cells, nphp1KO mice and NPH1 patients’ kidneys, Kibra, p‐MST1/2, p‐LATS and p‐YAP exhibited a notable increase in levels, with an even greater elevation observed in renal cyst cells, indicating the Hippo pathway activated in these nphp1‐deficient contexts. Here, MST1 is linked to cystic kidney disease.