The victory becomes the Tigers 20th First Grade flag.
The Tigers backed their bowlers in to draw first blood, sending the Mariners to the crease to bat first.
The decision from captain Nicholas Hobson immediately bore fruit for the Tigers, with big-name inclusion Joel Paris trapping Tyler Robertson in front at 1-16.
The situation went from bad to worse for the Mariners, as Matthew Kelly led the Tigers’ to an all-out bowling rampage.
Wickets dropped like flies for the Mariners, as the ladder-leaders crumbled under the intense pressure from Claremont-Nedlands.
Struggling to find a decent partnership, the Mariners lost eight wickets in the space of 94 runs, falling to 9-110.
Leon Coombs and Kane Standing produced the best partnership for the day, scoring 38 runs in the tenth-wicket partnership to push the total to 148, before Kelly took his fourth wicket, removing Coombs for 29.
Kelly was instrumental for the Tigers, finishing with terrific figures of 4-40, while Paris chipped in nicely with 3-28.
Needing 149 for victory, Jacob Whiteaker and playing coach Jim Allenby exploded the second they hit the crease.
The powerful pair completely dismantled the usually-reliable Mariners’ bowling attack to produce a stunning 111-run opening stand.
A quick fightback from Coombs, Damien Burrage and Craig Simmons saw three wickets fall in the space of 30 runs for the Tigers, however, the damage had already been done, as Brad Hope and Whiteaker hit the winning runs to secure the Tigers’ back to back Grand Final victory.
Allenby saved his best personal performance of the season for when it mattered most, scoring 66 from 103 balls.
Whiteaker finished with a hard-fought and unbeaten 54 from 154 to claim back-to-back Player of the Match honours.
Rockingham-Mandurah 148 (Coombs 29, Day 26, Kelly 4-40) defeated by Claremont-Nedlands 3-152 (Allenby 66, Whiteaker 54no, Simmons 1-24)