The tall Dominican-born de la Renta dressed New York socialites, Hollywood stars and American first ladies during a career that spanned five decades.
Former U.S. Secretaries of State Henry Kissinger and Hillary Clinton, former New York Mayor Michael Bloomberg and Vogue magazine Editor in Chief Anna Wintour spoke during the service at the Church of St. Ignatius Loyola on Manhattan's Upper East Side.
"It was a beautiful ceremony," said Heather Petrie, 31, a member of the choir. "It was a celebration of life" with "lots of music, an orchestra, a full choir and a soloist."
Music executive Lisa Schiff described the service as "extraordinary" as she left the church.
Designers Valentino, Diane von Furstenberg, Tommy Hilfiger and Donna Karan, director Mike Nichols and his journalist wife Diane Sawyer, newswoman Barbara Walters, photographer Annie Leibovitz and actor Hugh Jackman were among the invited guests.
Fans and photographers were kept behind police barricades that stretched a city block at the imposing church on Park Avenue.
"He was an icon and a guru of fashion and a wonderful man who changed people's lives in fashion," said 44-year-old Kim Wolfe of Manhattan as guests arrived for the service.
"His couture and his design were really created for the sophisticated lady, not necessarily of the 21th century, but of a lady that once was," she added.
De la Renta died at his home in Connecticut on Oct. 20, surrounded by his family, friends and more than a few dogs. As news of his death spread, fellow designers, Hollywood stars and former first ladies whom he dressed expressed their condolences.
De la Renta's designs were known for their detail, fabrics and embroideries. His classic creations ranged from fitted suits to pastel and floral print dresses to elaborate, flowing ball gowns that were favorites on the red carpet.
Actresses Sarah Jessica Parker, Amy Adams, Jennifer Garner, Tina Fey, Cameron Diaz and Oprah Winfrey chose his gowns for award ceremonies.
Most recently, de la Renta created the lace, off-the-shoulder wedding gown worn by London-based human rights lawyer Amal Alamuddin for her September wedding to actor George Clooney in Venice, Italy.
De la Renta was also known for his philanthropy, particularly in his native Dominican Republic, where he had a home. In 1982 he established La Casa del Nino for underprivileged children there.
President Danilo Medina led the nation in mourning and praised the designer for changing the lives of thousands of children in the country.
Dominican Foreign Minister Andrés Navarro credited de la Renta for being "a permanent ambassador of our country abroad" and for raising the nation's international profile.
