Sneyd became the first player to win the Lance Todd Trophy - as Cup final man of the match - outright in successive years.
He was the difference between the teams, landing three conversions to George Williams’ one after the six tries were shared.
Hull waited 87 years to win at Wembley and have now done it twice in 12 months.
They were deserved victors, though Wigan went agonisingly close to at least sending the tie into golden point extra time during a frantic finale.
Hull went behind early on, but hit back to lead 12-10 at the break and went further in front within 10 minutes of the resumption, though their failure to kill the game alm,ost cost them late on.
Wigan made a bright start and there was little between the sides in the opening 40, but Hull were by far the better team for 30 minutes after the interval.
At 18-10 with 10 minutes left Hull looked well in command, but Wigan clawed their way back into it with their third try and they were close to adding a fourth on two occasions in the last three minutes.
Overall though, Wigan were second-best. They made a series of errors and lacked the creativity Hull had in their halves. Hull’s first two tries came from kicks by Sneyd and he landed a 40-20 to set the field position for their third.
Mahe Fonua was also magnificent for the East Yorkshire club, crossing twice and having a third touchdown ruled out. He also cleared his lines strongly and was powerful in defence.
Wigan opened the scoring after just four minutes Jamie Shaul, the Hull full-back, allowed Thomas Leuluai’s kick to bounce, which it did kindly to Anthony Gelling and his pass sent John Bateman over.
Williams added the extras, but Hull worked their way into the game and were ahead by the end of the first quarter.
Their initial try came in a set after Liam Farrell was penalised for an incorrect play-the-ball near Hull’s line.
Liam Watts, who was outstanding in Hull’s pack, almost forced his way over and on the next play Albert Kelly off, loaded to Sneyd, who kicked to Hull’s left side.
Carlos Tuimavave leaped above Liam Marshall to make the catch and then narrow the angle enough to give Sneyd a relatively straight-forward conversion.
marshall came in at the last minute after Tom Davies was ruled out due to an ankle injury.
On 19 minutes Sneyd kicked towards the other flank, Kelly knocked the ball back and Fonua picked up in acres of space to go over unopposed.
Sneyd again improved the try - which was confirmed by video official James Child - but Wigan narrowed the gap after a long spell of pressure.
Sam Tomkins was close to scoring, but knocked on as he tried to reach over through Sneyd and Tuimavave’s tackle.
Moments earlier a Tomkins offload had gone to ground deep in Hull territory and Josh Griffin picked up with a clear run to the line.
It looked like referee Phil Bentham would allow the centre to play on - and presumably then refer to the video assistant, but he called a knock-on.
Sneyd and Tomkins had a set-to after the Wigan man’s knock-on, but Bentham took no further action - other than awarding a scrum to Hull - after a word with both captains.
It appeared Hull had weathered the storm, but Tuimavave fumbled inside the black and whites’ half and that led to Wigan’s second try.
On the last tackle they moved the ball left through Sean O’Loughlin and Leuluai to Williams and his excellent pass was finished by Oliver Gildart, though Williams could not convert.
Hull were close to extending their lead soon after the break when only a tremendous tackle by Tomkins kept Kelly out, then Griffin - agonisingly - spilled Sneyd’s kick over the Wigan line.
On 49 minutes Sneyd landed a brilliant 40-20. At the end of the resulting set Kelly slipped out a superb offload to Fonua and he made a fantastic one-handed touchdown.
Child confirmed Bentham’s initial indication of ‘try’ and Sneyd opened a two-score gap with his goal from the touchline.
Fonua thought had completed his hat-trick a minuted into the final quarter, from Shaul’s pass, but Bentham said no try and his video assistant Child agreed, deciding Griffin had obstructed Gildart.
Seconds later Child was called on again after Tony Clubb forced his way over. Bentham said no try and the Wigan man clearly lost possession, but there was a suspicion Tuimavave had pulled the ball out.
After several looks Child backed up the man in the middle. Wigan gave themselves hope with seven minutes left when O’Loughlin found Farrell and his long pass was well finished by Joe Burgess, though it was too far out for Williams to add the extras.
Williams was inches away from levelling the scores, but Jake Connor, Kelly and Shaul - who had a fine game after his shaky start - combined to keep him out.
Then, with 46 seconds left, Joe Burgess raced over from Farrell’s pass, but Bentham spotted that William’s ball to the second-rower had been forward.
Hull FC: Shaul, Fonua, Griffin, Tuimavave, Talanoa, Kelly, Sneyd, Taylor, Houghton, Watts, Manu, Minichiello, Ellis. Subs Connor, Bowden, Washbrook, Green.
Wigan Warriors: S Tomkins, Marshall, Gelling, Gildart, Burgess, Williams, Leuluai, Nuuausala, McIlorum, Clubb, Farrell, Bateman, O’Loughlin. Subs Isa, Sutton, Tautai, Powell.
Referee: Phi Bentham (Warrington). Attendance: 68,525.