Unadkat's nine-wicket haul helped Saurashtra wrap up a one-sided contest inside three days.
After bowling out Vidarbha for 151 in their first innings, Saurashtra had scored 375 in their opening essay to take a massive 224-run lead.
Vidarbha today resumed on 17 without loss in their second innings, but lost nine wickets for an addition of just 122 runs.
Vidarbha were bowled out for a mere 139 shortly after tea on day three with Unadkat (4/35) and medium pacer Deepak Punia (3/32) doing the maximum damage.
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Kamlesh Makvana (1/12) and Chirag Jani (1/21) took wicket apiece.
Vidarbha failed to find the rhythm and lost wickets in clumps with the highest partnership of the innings being the 44-run fifth-wicket stand between Ravi Jangid (10) and Wasim Jaffer, who top scored with 48.
In fact, only four Vidarbha batsmen could manage to reach the double-digit mark.
Brief scores:
Saurashtra: 375 (Jogiyani 130, Jackson 122, Yadav 5-81)
Vidarbha: 151 & 139 all out in 68.1 overs (Wasim Jaffer 48, Jaydev Unadkat 4/35, Deepak Punia 3/32).