Christine Swidorsky carried Logan Stevenson on her shoulder at the Saturday afternoon wedding in Jeannette, a suburb of Pittsburgh, the Pittsburgh Tribune-Review reported.
Logan stood with his grandmother, Debbie Stevenson, during a 12-minute ceremony uniting Logan's mother and his father, Sean Stevenson. The boy has leukemia and other complications.
"We're married," Swidorsky exclaimed joyously after kissing her groom to applause from family and friends.
After a whirlwind week, the Jeannette couple tied the knot in a hastily arranged backyard ceremony that formalized their union and celebrated Logan's life, which doctors say will be cut short soon by cancer.
The Stevensons abandoned an original wedding date of July 2014 after learning from doctors late last month that their son had two to three weeks to live. The couple wanted Logan to see them marry and to be part of family photos.
Logan dozed off and on during the ceremony, nestled on his grandmother's shoulder, the Pittsburgh Post-Gazette reported. Debbie Stevenson said he is on medication to make him comfortable, but it also makes him sleepy.
Swidorsky's mother died six years ago and her father died just two months ago, the newspaper said.
Logan, who was born Oct. 22, 2010, was diagnosed shortly after his first birthday with acute myeloid leukemia. He has Fanconi anemia, a rare disease that often leads to cancer.
He endured a stem cell transplant in July 2012. Last March, he underwent surgery to remove a kidney ravaged by a tumor.
During a Make-A-Wish trip to Disney World in June, Logan fell ill. He was hospitalized in Florida before he was flown back to Pittsburgh.
During a trip to the emergency room last month, a test revealed a mass in his remaining kidney, which led to his terminal prognosis. Logan is spending his remaining days at home, where he is showered with attention from family members.
Swidorsky's daughter, Isabella Johns, 13, served as bridesmaid and the couple's 1-year-old daughter, Savannah, was her parents' flower girl.
"This is our dream come true," Swidorsky said through tears, the Post-Gazette reported.