The Briton took full advantage of his first series pole to lead from the start, while fellow front-row man and RML Chevrolet team-mate Yvan Muller lost out fighting for an inside line at Turn 2 and could not prevent Monteiro slipping by around the outside.
From there the duo began to ease away from the field, while Muller started to fall back into the clutches of the chasing Bamboo Chevrolets of Alex MacDowall and James Nash.
The top five ultimately stayed in that order for the remainder of the race, although Chilton had to withstand several attacks from Monteiro before he was finally able to stretch the gap past one second three laps from the end.
Muller was never in the hunt for victory, but was at least able to edge away from MacDowall and Nash to seal a lonely third.
Gabriele Tarquini had a similarly solitary drive to sixth, just under 15s down the road from Chilton.
It was far more frantic lower down the field, with defending champion Rob Huff bunching up a multi-car fight that grew to include Tom Coronel, Marc Basseng, Stefano D'Aste, Pepe Oriola and Tom Boardman, who had started from 20th position.
Coronel finally found a way past Huff's stubborn defence three laps from the end, and was able to pull a three-second gap by the flag.
Huff hung on to finish eighth ahead of Basseng, with D'Aste completing a trio covered by just 1.5s at the line.
Oriola beat Boardman to 11th by less than half a second.
Just behind them an eight-car battle raged for much of the race, with Lada's James Thompson able to defend 13th until the final laps, when Michel Nykjaer and Hugo Valente - both forced to start from the back of the grid - came through.
Results - 13 laps:Pos Driver Team/Car Time/Gap
1. Tom Chilton RML Chevrolet 23m24.716s
2. Tiago Monteiro Honda +2.161s
3. Yvan Muller RML Chevrolet +6.534s
4. Alex MacDowall Bamboo Chevrolet +10.659s
5. James Nash Bamboo Chevrolet +12.676s
6. Gabriele Tarquini Honda +14.897s
7. Tom Coronel ROAL BMW +18.530s
8. Rob Huff Munnich SEAT +21.561s
9. Marc Basseng Munnich SEAT +22.558s
10. Stefano D'Aste PB BMW +23.266s
11. Pepe Oriola Tuenti Chevrolet +26.219s
12. Tom Boardman Special Tuning SEAT +26.653s
13. Michel Nykjaer Nika Chevrolet +35.488s
14. Hugo Valente Campos SEAT +37.826s
15. James Thompson Lada +40.811s
16. Fernando Monje Campos SEAT +41.457s
17. Fredy Barth Wiechers BMW +41.469s
18. Charles Ng Engstler BMW +41.971s
19. Franz Engstler Engstler BMW +42.242s
20. Mehdi Bennani Proteam BMW +42.805s
21. Mikhail Kozlovskiy Lada +43.997s
22. Norbert Michelisz Zengo Honda +48.934s
23. Rene Munnich Munnich SEAT +1m08.203s
Darryl O'Young ROAL BMW 5 laps
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