The runaway leaders of the division made the perfect start in front of 72,000 people when defender Aden Flint rose highest to nod home a corner with 15 minutes on the clock.
After Jordan Cook rattled the crossbar the Robins doubled their lead through wing-back Mark Little’s close-range effort and they never looked like surrendering that comfortable cushion.
The final whistle meant City, 10 points clear at the top, could add this season’s trophy to those lifted in 1986 and 2003 and set their sights on more celebrations in the coming weeks.
Favourites City headed to the national stadium for the first time since 2008 on the back of a eight-game unbeaten run and birthday boy Luke Freeman almost set them on their way in style inside five minutes only for his fizzing long-range effort to fly just over the crossbar.
At the other end Frank Fielding comfortably gathered Anthony Forde’s effort as Walsall began to settle in the first-ever Wembley trip in their 127-year history.
Flint came into this tie with five goals in his last nine games and with just 15 minutes on the clock the centre-back climbed above Paul Downing make it 10 for the campaign.
Marlon Pack’s corner was swung to the back post and there was the former Swindon defender, who had previously never scored more than four in a season, to gleefully butt home.
Kieran Agard was one of two changes to Steve Cotterill’s starting line-up and the former Rotherham man, back at Wembley less than 12 months after celebrating promotion with the Millers, came extremely close to putting the game to bed five minutes later.
Having wriggled goalside of his marked the striker was denied by a fine James Chambers block as he prepared to pull the trigger.
Chances followed for captain Aaron Wilbraham and Pack as City looked to put the game to bed but they were given a scare three minutes before the break from the left foot of Andy Taylor. A ball was headed back into Taylor’s path and he unleashed a thumping effort that dipped just over Fielding’s crossbar.
That let off meant City supporters spent the half-time interval discussing the need for a second to kill off the hard-working Saddlers and they found it just six minutes later through the unlikely source of Little.
Freeman swung in a cross and Little’s initial header was kept out by Richard O’Donnell but the unfortunate goalkeeper could only push the ball back onto the knee of the former Peterborough man who could celebrate just his second of the season.
City may have cruised to victory but not without a 58th-minute scare when Cook’s left-wing cross caught out everyone, including Fielding, but rattled off the crossbar and Tom Bradshaw failed to force the rebound over the line from inside the box.
Despite a string of substitutions the blunt Saddlers attacked failed to really test Fielding and like on so many occasions this season the League One leaders comfortably saw out the remainder of the match.