West Brom striker Diomansy Kamara scored a superb individual goal to help Tony Mowbray's side move within one point of second-placed Birmingham in the Coca-Cola Championship.
The Senegal international, who also scored the opener from the penalty spot, took his goal tally for the season to 17 as Albion registered a fifth successive win in all competitions.
It was also the seventh league win on the trot at The Hawthorns - although a late Plymouth rally nearly proved costly for the Baggies with substitutes Sylvain Ebanks-Blake and Scott Sinclair a real handful.
Kamara's strike partner Kevin Phillips and new midfielder Robert Koren also impressed for Albion.
Kamara had tormented Wolves in Sunday's FA Cup tie and he was soon causing problems for the Plymouth rearguard.
One pacey run saw him skip past three challenges before cutting into the area but he failed to spot the unmarked Jason Koumas and his eventual shot was blocked.
Referee Mike Thorpe has spotted a foul by Hasney Aljofree during the course of Kamara's run but waved play on before eventually booking the Plymouth defender.
Koumas then whipped in a testing low centre from the right flank and Kamara was first to react but his first-time shot flew a couple of feet wide.
Albion enjoyed the majority of possession in the early stages and, when Plymouth did venture forward, Kiely clung on confidently to a 25-yard free-kick from Peter Halmosi.
Baggies defender Paul Robinson was yellow carded after 32 minutes for a wild lunge on David Norris who a few seconds earlier had prevented him from taking a quick throw-in.
Then after 41 minutes Kamara broke the deadlock from the penalty spot.
Neil Clement's throw-in was flicked on by Paul McShane - and Buzsaky was adjudged to have handled.
There were few complaints from the Plymouth players before Kamara stepped up to beat the dive of McCormick with a low shot into the left hand corner of the net.
Robert Koren could have made it 2-0 a minute before the interval but his diving header went wide from Phillips' centre.
Hayles would have been disappointed not to have at least hit the target in the early stages of the second period after bursting into the Albion box.
But after 50 minutes Tony Mowbray's side doubled their lead with a Kamara's individual effort.
A superb first touch when controlling a Phillips crossfield pass created a yard of space and then an electrifying burst of pace took him past two defenders and away from the challenge of McCormick before netting from a narrow angle.
Koren is giving every impression of adjusting to the pace of English football after his move from Lillestrom and one cross from the Slovenian international was scooped over the bar at full stretch by Chaplow.
Kiely clung to a header from Hasney Aljofree in a rare moment of danger from Plymouth - but in the 70th minute substitute Rory Fallon gave Ian Holloway's side a lifeline.
Buzsaky clipped the ball into the box and Fallon had time to drive a left-footed volley past Kiely.
Ebanks-Blake was denied an equaliser by a goal-line clearance by Paul Robinson - although Plymouth boss Ian Holloway thought his player had been caught by Kiely before he dinked the ball over the goalkeeper.
Teams
West Brom Kiely, McShane, Clement, Curtis Davies, Robinson,Koren, Greening, Chaplow, Koumas (Gera 65),Kamara (MacDonald 76), Phillips (Carter 85).
Subs Not Used: Daniels, Hodgkiss.
Booked: Robinson, Chaplow.
Goals: Kamara 41 pen, 50.
Plymouth McCormick, Connolly, Aljofree, Seip, Capaldi, Norris,Nalis, Buzsaky, Halmosi (Sinclair 53),Hayles (Ebanks-Blake 73), Gallen (Fallon 65).
Subs Not Used: Timar, Summerfield.
Booked: Aljofree, Capaldi, Nalis.
Goals: Fallon 70.
Att: 19,894
Ref: M Thorpe (Suffolk).