Just four days after saying "I do" to Kanye West, Kim Kardashian took to social media to declare that she has adopted her new husband's last name.

On May 28, the 33-year-old reality star changed her monikers on Instagram and Twitter from Kim Kardashian to Kim Kardashian West.

According to inside sources, Mrs. West knew well in advance that she would change her famous last name after she walked down the aisle.

"Kim knows that she will be with Kanye forever. They share a child together and they will share their life with each other, so taking his name was exactly the thing she had planned with Kanye all along," an insider told HollywoodLife.com exclusively.

Back in Oct., the TV personality told E! News that she planned to change her name just days after the hip hop star proposed to her on Oct. 21 on her 33rd birthday.

"I will," she told E! while celebrating her birthday in Vegas on Oct. 29. "It'll be Kim Kardashian West. No, not hyphened. Make it the middle."

The newlyweds exchanged vows in a lavish wedding ceremony in Florence, Italy on Saturday, May 24. 

According to reports, the Mr. and Mrs. are currently honeymooning in Ireland on a five-day vacation, reports The Hollywood Gossip.

ABC News reports that the couple kicked off their honeymoon on Tuesday by enjoying a beautiful day on Ireland's Ballyhoura Mountains, which are located in southeast County Limerick and northeast County Cork in central Munster.  "Kimye" joined a group of six on mountain biking adventure along picturesque trails, said manager Fergal Somers to ABC News.

While on the hike, they spotted rare birds of prey, the red squirrel, deer, foxes, butterflies and a swarm of honeybees.

Afterward, West and Kardashian enjoyed a picnic with local artisan food that included a Trail Tart, smoked ham with old Irish creamery cheddar, a spicy apple salad, a lemon posset, brownies and tea and apple juice.

The couple reportedly ordered a pint of Guinness after leaving the mountain and are said to be staying down the road at a very large residence.