The 12-year-old defeated the top three seeds on his way to making history, breaking a record that had been in place for 48 years after Kevin Beadsley won the title aged 13 in 1974.
It was a stunning performance from Sellado, who started the day as the ninth seed. His display came just two weeks since returning from a European training camp in the Czech Republic, where he was rated as the second-best player in his age group across the continent.
He added the junior title for good measure, defeating two-time Halifax men's champion Ben Fillingham in five ends.
It was Shaun Ellis who he defeated in the final, beating the top seed for the first time in a majestic 3-1 showpiece. Sellado's speed and power were simply too much for Ellis, who tried valiantly to stick in rallies and force errors out of the youngster, but his improved consistency in longer exchanges proved the catalyst for the win. Sellado took the first end before Ellis stormed back to level the game comfortably. From that point, Sellado demonstrated his qualities in fine fashion.
His route to the final saw Sellado first defeat Gareth Hey before encountering second seed Richard Aitken in the last 16. A string of superb exchanges saw Aitken retrieve wonderfully from the back of the court, but again, Sellado's ability to remain strong and consistent eventually saw him prevail.
Arguably his biggest scare came against eighth seed James Foster, who twice came from a set down to take it to a decider. But the fearless Sellado raced into a strong lead and eventually broke down the resolve of his older opponent, who had blocked tremendously throughout.
The semi-final saw Sellado play third seed Matthew Shaw, who hadn't dropped an end on his path to the last four, beating younger brother Alex in the quarter-finals. Crucially, Sellado saved a game point to win the opening end 12-10 before Shaw fired back to win the second 11-8. However, Shaw's aggressive approach eventually produced errors while Sellado remained errorless. Shaw overturned a 7-1 deficit in the third end to bring it level but Sellado eventually came through and took the fourth end with relative ease.
On the other side of the draw, Ellis had defeated fourth seed Cameron Sandhu in the semi-final 3-2 to avenge two defeats in the past month. He had previously overcome Russell Senior and Liam Chipman, the latter of whom knocked out defending champion Fillingham in the last 16. Sixth seed Ian Marshall also went out at the same stage, losing to 14th seed Naz Ahmed, who gave Sandhu a scare in the quarter-finals.
Matthew Shaw picked up his fourth doubles title, prevailing with Ben Fillingham. The two top-seeded pairings reached the final, with Richard Aitken and Lewis Palmer advancing with a victory over Sellado and Jake Clarke in five ends.
Shaw and Fillingham had to overcome a scare in the semis to defeat Ahmed and Phil Mann, who had dumped out fourth seeds Alex Shaw and Liam Chipman in the round before.
The final was a back and forth exchange with both pairings going through patchy periods at the end of a long day. Eventually, Shaw's backhand, backed by Fillingham's explosive forehand, saw them come through 11-9 in the fifth. Shaw still has some way to go to overcome Alan Dickinson's record of nine doubles titles.
The veterans event was won by Aitken, who continued his recent good form by defeating Ellis in the final 3-1. Aitken had overcome Marshall to reach the final while Ellis dispatched of team-mate Senior to advance.
The Division 1 banded event was won by Jo Keighley, who defeated Mann in the final after a string of tight games across the event.
Salamat Hussain was a surprise winner of the Division 2 competition, starting as sixth seed but defeating top seed Phil Gatehouse in the final, who he had initially lost to in the group stages before winning when it counted.
Teenager Alfie Mawson produced an impressive display to win the Division 3 event, overcoming teammate Adrian Kelly in the final. Mawson had previously given Fillingham an almighty scare in the junior semi-final, losing 3-1.