The Spaniard started the race from pole position on his Pons Kalex, but found himself trailing fast-starting Britons Bradley Smith (Tech 3) and Scott Redding (Marc VDS Kalex) in the early stages of the race.
While Smith fell off the pace quite quickly, Redding managed to lead until the mid-point of the race. But with 11 laps to go Espargaro made his move into Stowe, before sprinting away to take a comfortable win.
Behind Espargaro, Redding and Marc Marquez (Monlau Suter) staged a thrilling fight for second place. Having spent the last 10 laps swapping positions, things got serious on the final lap, the pair trading blows right down to the last corner.
But Redding did enough to hold on for a stunning second place, while Marquez took over the championship lead with third.
Andrea Iannone (Speed Master Speed Up) took fourth having run with the frontrunners throughout the race, although he did have to stave off a late challenge from Simone Corsi (Ioda FTR), who ended up fifth.
Smith made one of the starts of the season to lead into Abbey from the second row, but quickly found himself fighting with the bike. He ended up slipping down to seventh, book-ended by Claudio Corti (Italtrans Kalex) in sixth, and former championship leader Thomas Luthi (Paddock Suter) in eighth.
British Moto2 results:
1. Pol Espargaro (Spain) Kalex 38:29.792
2. Scott Redding (Britain) Kalex 38:31.254
3. Marc Marquez (Spain) Suter 38:31.313
4. Andrea Iannone (Italy) Speed up 38:32.643
5. Simone Corsi (Italy) FTR 38:33.595
6. Claudio Corti (Italy) Kalex 38:36.901
7. Bradley Smith (Britain) Tech 3 38:37.419
8. Thomas Luethi (Switzerland) Suter 38:37.461
9. Dominique Aegerter (Switzerland) Suter 38:45.639
10. Mika Kallio (Finland) Kalex 38:49.971
11. Alex de Angelis (San Marino) Suter 38:50.242
12. Toni Elias (Spain) Suter 38:52.809
13. Esteve Rabat (Spain) Kalex 38:52.947
14. Randy Krummenacher (Switzerland) Kalex 38:53.028
15. Ratthapark Wilairot (Thailand) Moriwaki 38:54.299