The rise in the domestic and industrial applications of granite and float glass which are hard and brittle is forcing manufacturing engineering to develop their precise and cost-effective machining techniques. These materials are used mainly in buildings, decorations, arts and optics industries which require a perfect surface finish and dimensional accuracies. Rotary ultrasonic face milling (RUFM) is preferred among all non-conventional machines for surface grinding. The main objective of this paper is to analyze the effect of process parameters on RUFM on float glass and red granite. The analysis of variance (ANOVA) method was used to find significant factors and determine interaction effects as well. Both the materials were compared for material removal rate (MRR) and surface roughness (SR) as response variables. In addition, SEM (Scanning Electron Microscope) was used for qualitative tool wear analyses and comparison between both materials after milling. The experimental results show that the MRR and SR during RUFM increase with all input parameters. Also, the process parameters have a significant effect on output responses. It was concluded that RUFM can successfully be used for brittle and hard material to obtain a micro-level surface finish with a normal material removal rate. In addition, it is surmised that more hardness of work material reduces the tool life.