The couple, who became engaged in April after O'Sullivan popped the question on a trip to Lake Garda, Italy, exchanged vows at St Mary and Laurence Church in Athy, Co Kildare, in a service which saw a number Dublin football's All-Stars come out in celebration.
The bride, who works in communications, went for a boho bridal style, with a trumpet silhouette gown featuring a boned corset and semi-sheer lace train. Most striking was her homage to to days gone by with a double pearl strand hair band which held her cathedral length veil in place as she clutched a bouquet of wild flowers.
A vintage theme was carried throughout as the bride arrived with her father Gary via a classic red Jaguar dating back to the '70s. Her bridesmaids, comprised of her sister and close friends, were dressed elegantly in silk dove grey gowns with floral overlay. They held vintage parasols to protect them from the rain, which abated just enough for the happy couple to enjoy some pictures outside the church - their first as newlyweds.
O'Sullivan chose a classic tuxedo with a black velvet jacket and grey bow tie. The pair beamed as they posed for photos after the ceremony, before heading to a country house in Wicklow for a party to remember this evening. In order to assuage guests battling a December chill, the couple also hired a mini-van from artisan coffee company Cocobrew for guests.
O'Sullivan's Dublin teammates Stephen Cluxton and his wife Joanne O'Connor led the VIP guests in attendance, two years after their own nuptials, while newlyweds Paul Flynn and Fiona Hudson, who celebrated their first wedding anniversary last week were also in attendance.
Their parents together announced their engagement via a formal notice in a national newspaper, which mentioned Cian's GAA home at Kilmacud Crokes, saying: "Danielle and Cian together with their parents Olivia and Gary, Foxrock and Noreen and John, Kilmacud are delighted to announce their engagement.
Speaking previously about her other-half’s high profile, Danielle said that he is “just Cian” to her. “I am well aware he has quite a few female fans too,” she laughed to Independent.ie Style. “But that comes with the profile. He is a super grounded guy and I knew him long before he was playing for Dublin and nothing has changed for us.
“It is really lovely to see young kids and fans asking for pictures, but it’s funny at the same time because he's just Cian to me.”
For all the pictures from the big day, check out our gallery below: