The young striker netted once in each half, following up on Craig Dawson's opener, before Graham Dorrans added a fourth just before the end of normal time at the Hawthorns.Burnley remains winless in the Premier League after beating comfortably beaten 4-0 by West Brom at the Hawthorns.
Craig Dawson opened the scoring on the half-hour mark, heading home a corner from Chris Brunt, with the home side in control of the game.
Striker Saido Berahino then netted a double, one just before halftime and the other in the 56th minute, both times combining with the impressive Graham Dorrans.
Dorrans completed the rout just before the end of normal time with a cool first-time finish set up by Cristian Gamboa.
That the Baggies' first two goals came as a result of sloppy Burnley defending from corners will give manager Sean Dyche plenty to ponder, especially as the Lancashire club traveled to the Hawthorns on the back of three straight clean sheets.
On this evidence, Dyche has a big job on his hands to keep his side in the top flight, while West Brom celebrates a second league win of the campaign.
The home side's starting XI was unchanged from the win at Tottenham, while Burnley, which was again without injured trio Danny Ings, Sam Vokes and Matt Taylor, brought in former Baggies player Steven Reid in a holding-midfield role, Ross Wallace and Michael Kightly to replace Marvin Sordell, David Jones and Dean Marney.
The visiting side had an early penalty appeal turned down when George Boyd's cross struck Andre Wisdom on the shoulder but otherwise offered little in attack and tried to focus on keeping it tight at the back.
The resistance was broken after half an hour, though, when Dawson climbed high above Jason Shackell at the back post to head in a Brunt corner for his first West Brom goal since joining from Rochdale four years ago.
Tom Heaton had to be alert to stop the home side from going further in front when tipping a long-range Dorrans strike over the bar but a second goal did arrive in first-half stoppage time when Berahino nodded in from close range after Dorrans had flicked on a James Morrison corner.
Dyche reacted at the interval by bringing on Ashley Barnes and Nathaniel Chalobah for Reid and Wallace. Chalobah's first taste of action earned him a booking for a lunge on Craig Gardner, who soon after went close with a long-range strike, while Stephane Sessegnon's volley was well blocked by Ben Mee as the home side continued to boss proceedings.
Good work from Brunt and Dorrans then put Berahino clean through on goal and he fired low past Heaton on 56 minutes to make it three.
West Brom goalkeeper Ben Foster was forced to make a smart save after Lukas Jutkiewicz rose above Dawson and headed powerfully on target and Barnes should have done better when set up by third substitute Sordell.
Dorrans made it 4-0 after 90 minutes following good work down the right by substitute Gamboa, neatly tucking his low shot past the outstretched Heaton to send Burnley bottom on goal difference.