Coach Simon King was full of praise for the Welsh effort.
"This game was an accumulation of all the hard work done by a lot of people this season at age grade rugby in Wales" said King.
"The boys have worked conscientiously throughout the year and have always wanted to play attacking and adventurous rugby. Italy may not have been at their strongest but we kept our shape and style throughout and scored some tremendous tries. The future is bright."
Italy started with spirit and pressed the Welsh line but it was Wales who took the lead after seven minutes when Walker finished off an overlap to scoot in at the corner. The Ospreys flier then slalomed his way in from the half-way line to get a fine solo try, converted by fellow Osprey, fly-half Matthew Morgan who had to do the same thing three minutes later after putting Blues lock Cory Hill in at the posts.
Wales were a different class, centre George North sending his fellow Scarlet and scrum-half Aled Davies scuttling home before skipper and flanker Calum Thomas got the fourth converted try inside eight minutes.
With Wales running everything, the agony continued for the Italians with Walker getting his hat trick to make it 40-0.
The stunned Azzurri resisted briefly but North collected his side's seventh first-half try just before the break and there was still time for Morgan to slip through a grubber kick, collect it and run in under the posts for a 54-0 lead.
Wales made a raft of changes but service was resumed within eight minutes when lock Matthew Screech charged over for replacement fly-half Joseff Griffin to convert.
Walker dived over for his fourth try soon followed by a galloping run and score for replacement lock Luke Hamilton.
Walker rubbed further salt into the wound with Wales's twelfth and with players now queuing up to get on the score-sheet, hooker Kirby Myhill added his name to the growing list.
Would the hosts get a century of points was the only interest left in the game. A try by flanker Ellis Jenkins and Griffin conversion made it likely at 94-0 with seven minutes left, but Italian replacement Ippolito Menniti then raised a cheer with a penalty for Italy who clung on bravely to stop Wales getting the 100 points.
Wales: Tries - E Walker (5), C Hill, A Davies, C Thomas, G North, M Morgan, M Screech, L Hamilton, K Myhill, E Jenkins; Cons - M Morgan (7), J Griffin (5)
Italy: Pen - Menniti
Wales Under 18: Tom Prydie (Ospreys) ( rep (H Thompson (Blues) h-t); Leighton Bellamore (Dragons), George North (Scarlets), Luke Williams (Scarlets) (rep S Campbell (Blues 37), Eli Walker (Ospreys); Matthew Morgan (Ospreys) (rep J Griffin (Blues) 42), Aled Davies (Scarlets) (rep T Habberfield (Ospreys) h-t); Rob Evans (Scarlets (rep D Harris (Blues) 30), Kirby Myhill (Scarlets), Will Griff John (Blues) (rep S Lee (Scarlets 22-30 and 49), Cory Hill (Blues) (rep L Hamilton (Scarlets) 43), Matthew Screech (Blues), Ellis Jenkins (Blues), Dan Baker (Ospreys) (rep T Young (Blues) 58), Calum Thomas (Blues) (capt)
In the other match of the final day of the Under 18 festival at Llandovery, Ireland beat Scotland 28-14 in a highly contested encounter.
Full Under 18 Five Nations Festival results (all Llandovery):
April 2 Wales 24 Ireland 18; England 29 Scotland 9
April 6 England 41 Ireland 17; Scotland 33 Italy 13
April 10 Wales 94 Italy 3, Ireland 28 Scotland 24