WA were bowled out for 148 on Thursday after making 137 in their first innings in reply to the home team's 419.
NSW owed their victory to a 10th wicket partnership of 219 between Dominic Thornely and Stuart MacGill, with man-of-the-match Thornely posting an unbeaten 261.
After that NSW's pace bowlers were consistently too good for the visiting batsmen.
Only former Zimbabwean Test batsman Murray Goodwin, with a half-century in each innings, offered any resistance.
Stuart Clark claimed 3-20, Matthew Nicholson 3-41 and Test leg-spinner MacGill 3-52.
At Sydney (day three): New South Wales 419 (D. Thornely 261 not out, B. Haddin 45; B. Casson 3-88) beat Western Australia 137 (M. Goodwin 55, R. Campbell 28; S. Clark 4-24, M. Nicholson 3-18) and 148 (M. Goodwin 58, B. Hogg 22; S. Clark 3-20, M. Nicholson 3-41, S. MacGill 3-52) by an innings and 134 runs.