The company announced the milestone on its official Twitter stream late Friday night.
Just over a week since launch and @VodafoneUK has already sold its 100,000th iPhone! #100k, the network announced.
Orange's exclusive contract with Apple recently ended, paving the way for Vodafone's entry.
The UK and French markets are the only European countries where the phone is not tied to exclusive carriers. The ending of the exclusive contracts historically bode well for Apple.
Since April the iPhone has been available through three main French operators after Orange's exclusive distribution ended in France.
The wider distribution caused Apple's market share to jump 32 percent in the latest quarter from 21 percent just three months earlier, according to research from Bernstein.
A surge could also take place in Germany, where only Deutsche Telekom's T-Mobile distributes the device so far, and Spain, where Telefonica remains the only distributor.
A strong take-up in European countries could cheer up investors concerned about initial disappointing demand in China.
China, with 350 million mobile users, represents a huge opportunity for Apple, but its high price may need to be more heavily subsidized to take off.
The iPhone is currently the main driver of growth at Apple, with more than 30 million units sold since its launch in 2007.
Analysts expect the company to ship 9 million iPhones during the quarter on average, with more optimistic expectations forecasting upwards of 11 million units.