In opening deals, London's benchmark FTSE 100 of major blue-chip companies added 0.1 percent to 7,225.15 points, compared with the closing level on Wednesday.
In the eurozone, Frankfurt's DAX 30 index won 0.2 percent to 13,167.56 and the Paris CAC 40 also added 0.2 percent to 5,871.20 points.
More than 4,000 polling venues across England, Scotland, Wales and Northern Ireland, have opened their doors for a day of voting that ends at 2200 GMT.
Up for grabs are all 650 seats in the British parliament, which has been deadlocked since the 2016 referendum on EU membership that saw a majority vote to leave.