The Italian (Liquigas-Cannondale) found a gap on the left-hand side of the road and was able to edge out his rivals to claim the leader's jersey as the final pro stage race of the season got under way in the Olympic Park.
Brit Andy Fenn (Omega Pharma - Quick-Step) continued his impressive debut season with second place, while Team Sky's Edvald Boasson Hagen sprinted to third after what had been a relatively straightforward opening stage.
12 laps of the Beijing city circuit always looked destined to end in a bunch sprint and so it proved, with a five-man breakaway reeled in to allow the sprinters a chance to stretch their legs.
Victory for Viviani saw the talented Italian move into a four-second lead ahead of a trip into the surrounding mountains on Wednesday.
The race kicked off with a brief run from the ceremonial start in Tian An Men Square over onto the circuit which would form the day's stage.
It wasn't long before the action got under way and it was Craig Lewis (Champion System) who kicked clear as the race hit the 7.8km Bird's Nest circuit.
The experienced American was joined by four more riders to share the workload, the move gaining a shade over two minutes but never any more on a short opener.
Orica-GreenEDGE and Liquigas-Cannondale were among the teams giving chase, each looking to set up their respective sprinters on the pan-flat but windy course.
With the break never too far out of their sight the day was always destined to end in a bunch sprint as new teams hit the front in the closing stages to set things up - Viviani emerging victorious.