At the 2015 UK Open, O'Connor overcame Dean Winstanley 5–3, Mark Webster 9–5 and Ian White 9–6 to reach the fifth round of the event for the first time where he played Stephen Bunting. The opening eight legs were shared, before Bunting took four of the next five and he went on to eliminate O'Connor 9–6. He saw off Ian White 6–1 and Vincent van der Voort 6–3 to reach his first quarter-final in three years and first in a European Tour event at the German Darts Masters. O'Connor led world number one Michael van Gerwen 3–1, but went on to lose 6–4 despite taking out three 100 plus finishes. O'Connor and Finnan's World Cup second round match with Hong Kong went to a doubles match which they lost 4–3. O'Connor was unable to advance past the first round of the World Grand Prix for the fourth time as he missed two match darts against Jamie Lewis.