The Crawley AC competitor finished in a time of 30min 32sec, which was enough to see him crowned 2018 winner in scorching conditions on Worthing Promenade.
Westlake's winning time was not the only record to fall on the day, the 2,365 runners that started the event surpassed the previous best for what was the 28th edition of the race.
Fast times were expected ahead of this year's Worthing 10k and the racers certainly delivered. Andy Greenleaf came home 27 seconds after Westlake (30:59) to secure second, while Jonathan Cornish (31:15) completed the top-three.
Crawley AC's Westlake, 26, who finished 27th in the London Marathon back in April, continued his stunning year by winning the Worthing 10k.
He said: "It's been a really good time for me since Christmas. I stopped playing football and I've seen a massive improvement.
"Winning the race was a little bit of a surprise as I came in with tired legs having competed in a couple of other events this week.
"It was such a strong field and the temperatures were very high so it was great to win the race.
"I'm really pleased with my efforts but that record is there to be beaten now."
Horsham Blue Star runner Elspeith Turner won the female race in a time of 37:24. Rebcca Bunting (37:52) was the next women to finish, with Emma Gill (39:32) the third female across the line.
Turner, 53, who raced for Scotland earlier in her career, bagged victory in the event for a second time.
She said: "This is the third time I've done the race and every time the weather has been lovely. I actually last competed when it was on the old course around ten years ago and managed to win it that year. I haven't been anywhere near winning since but I managed to come back and win it this year.
"It was a good time to win it in, it's normally won in around the time I recorded, I didn't see who was behind me and just focused on myself."