"There is still political uncertainty surrounding the European project. This is true in the broader context of our Union," Draghi told European Parliament during a session on the ECB's annual report for 2014.
"A solution that would anchor the United Kingdom firmly within the EU while allowing the euro area to integrate further would boost confidence."
One of the major issues for non-euro members such as the UK is that EU rules are made with the interests of Eurozone countries in mind, without due consideration of non-euro nations. There are 28 members of the EU, with 19 currently using the euro.
Draghi's comments come as Prime Minister David Cameron and European Council president Donald Tusk try to finalise a deal to keep the UK in the union. They are trying to put the deal together in time for an EU summit this month, where it will be put to other EU leaders.
The central bank chief also reiterated his view that the case for monetary policy easing had increased since the ECB's decision to boost stimulus measures in December.
"Downside risks have increased again amid heightened uncertainty about emerging market economies’ growth prospects, volatility in financial and commodity markets, and geopolitical risks. Inflation dynamics are also tangibly weaker than we expected in December," Draghi said.
He said that policy would be reviewed in March. In December, the ECB cut the interest it pays on deposits to minus 0.3 per cent from minus 0.2 per cent and extended its €60bn (£46bn) a month asset purchase programme by six months to March 2017.