In recent years there has been a huge increase in consumer interest in products with the reduced fat content and the additional health-promoting properties. The interactions between the fiber and the ingredients of the cheese sauce have not yet been investigated and described. The aim of the research was examination of the effect of pumpkin and kale fibers on hysicochemical properties and stability of the processed cheese sauces (PCS) obtained with the whey protein concentrate (WPC80), acid casein (AC) and different fat sources. In samples with the kale (KF) and rapeseed oil (RO) addition an increase in the value of characteristics such as hardness, adhesiveness, product stability (TSI) and surface roughness was observed. The results of measurements of storage (G′) and loss (G″) moduli showed the same upward trend with an increase in the amount of added kale fiber. They were related to the hardness and roughness parameters determined by measure of surface properties using the optical profilometer and the stability examined using Turbiscan. In the PCS with kale fiber addition based on RO an increase in stability (6.41–1.86 TSI) and roughness (2.2–16 qm) values along with the amount of fiber added was observed. Also optical microscopy images present the compacted structure of produced sauces. This article provides results and relevant literature, discussing the impact of different fibers and other ingredients on structure of PCS. In the future, these fibers may replace typical hydrocolloids used in processed cheese sauces production.