Emil Riis and Cameron Archer scored in a 2-0 win, their first success on Albion's home ground since October 1973.
It was a thoroughly-deserved three points against a Baggies side who are in the play-off positions and hadn't been beaten at home in the Championship this season.
But there was loud discontent from the home fans who chanted the name of their former manager Slaven Bilic and booed the team off at the final whistle.
PNE manager Lowe said: "We limited them to very little and scored two goals which is always pleasing.
"We nullified their strengths, we had worked on that for the last couple of days on the training pitch.
"We said to the group if you follow our instructions, we can get a result.
"Every single one of them to a man was fantastic and that is what we need off the group. We get it right together, not as individuals.
"West Brom try and drag you all over the pitch and I thought we were fantastic in not getting sucked into that.
"When you come away to The Hawthorns and scored two good goals, it is always pleasing.
"The fans were fantastic for us, singing right the way through. I know West Brom aren't doing as well as they would like and their fans were a bit quiet but you could hear our supporters from start to finish.
"Fair play, it was a brilliant turn out from them and we gave them something to go home happy with."