Machining Rapidly Solidified aluminium (RSA) 6061, a widely used optical material by Ultra-high precision diamond turning, has enabled high accuracy and surface integrity. However, improved quality and productivity require precision surface and machining process monitoring because the duo has a great influence on machine part performance. The study presented in this paper investigates the effects of cutting parameters (i.e., depth of cut, feed rate and cutting speed) on machining output variables (surface roughness and acoustic emission potentials) during ultra-high precision diamond turning of RSA 6061. With the aid of Box-Behnken design (BBD), a response surface methodology, and the analysis of variance (ANOVA), the correlation between cutting parameters and machining output variables were analyzed and modeled. The results showed that both surface roughness and acoustic emission potentials are greatly influenced by feed rate and cutting speed. For a better-quality surface roughness and low acoustic emission during ultra-high precision diamond turning of RSA 6061, high cutting speed and low feed rates are the right combinations and vice versa.