The world number one, who had previously lifted the title in 2022 and 2024, recovered from an uncertain start to secure his eighth European Tour success, extending a remarkable record in a venue that has become his own fortress.
Rock, Northern Ireland's top-ranked player, seized the early initiative with a 3-1 lead as Humphries struggled to find rhythm. Yet the Englishman responded with a spell of sustained scoring, only for Rock to halt his surge with a brilliant 153 checkout to level at 4-4.
The match turned in the eleventh leg, when Rock wasted three darts at double to tie matters at 6-6. Humphries punished him without hesitation, checking out 98 before pinning double ten to clinch victory and secure back-to-back Prague titles.
"I feel a little bit emotional to be honest," Humphries admitted. "I feel like every game I've played this weekend, I've felt the love from the crowd.
"You don't win three events in the same venue for no reason, so this is a special tournament for me."
Return to form for Humphries
The 30-year-old had endured a quiet spell since winning the US Darts Masters in June, and his European Tour form in recent months had looked below par compared to the standards set earlier in his career.
By his own admission, the Premier League triumph in May was followed by a dip in consistency, but finals day in Prague suggested he is rediscovering peak sharpness.
After labouring past Dirk van Duijvenbode on Saturday, Humphries was transformed on Sunday.
He opened with a 6-3 win over Martin Schindler, then produced a 103 average to claw back a 5-3 deficit against Wessel Nijman, surviving two match darts in the process.
His semi-final was even more emphatic: a 7-1 demolition of James Wade, marked by relentless scoring and clinical finishing.
"Since I've won the Premier League, it's been tough for me. I have been struggling, but it felt so good being up here tonight," Humphries added.
"Now I feel dangerous again. This is when you need to be at your best, at the back end of the year. I know if I want to stay as world number one, I have to put the effort in and work hard. I want to be World Champion again, so it all starts from now."
Rock's breakthrough continues
For Rock, the defeat marked his second consecutive European Tour final after finishing runner-up in Jena last weekend. His route to the final in Prague was nothing short of brutal, taking out a trio of Dutch opponents in clinical style.
He opened with a 103 average to beat three-time world champion Michael van Gerwen 6-4, then swept aside Jermaine Wattimena 6-1 with a stunning 110 average, before overpowering Gian van Veen 7-3 in the semi-finals.
His tournament average across the weekend hovered close to 100, a clear indication that his game is reaching elite consistency.
"Luke and I didn't play to our full potential there," said Rock, who captured the World Cup of Darts title earlier this summer.
"I never had a good record here in Prague, but now I've improved on that, and I'm happy with the last two weekends I've had. It's not every day you make back-to-back European Tour finals, and I'll get another title soon.
"I'm starting to be a proper dart player now, and I'm looking forward to the rest of the year, so it's on to the next one."
Standout performers
Elsewhere, Van Veen was among the standout stories of the tournament. The 22-year-old eliminated teenage sensation Luke Littler 6-4, ending Littler's 19-match winning streak on the big stage and making it three wins on the spin against the sport's brightest young star.
He then whitewashed Gerwyn Price 6-0 in the quarter-finals, despite the Welshman averaging 104, underlining his growing status as one of the most dangerous players in the field.
James Wade continued his European Tour resurgence by reaching a third straight semi-final, dispatching Nathan Aspinall, Ross Smith and Stephen Bunting before falling to Humphries.
Bunting himself had impressed earlier, knocking out 2023 champion Peter Wright after staging a comeback from 5-3 down.
With Humphries lifting silverware once again and Rock consolidating his reputation as a rising force, the European Tour narrative now shifts to Budapest for the Hungarian Darts Trophy on September 19th.
Van Gerwen will defend his crown there, but Humphries arrives in Hungary carrying renewed confidence that his grip on the number one spot will endure as the season edges towards its defining stretch.