The private service was held at St. Martin's Episcopal Church.
Approximately 1,500 guests are expected to be in attendance.
Dr. Martin Murphy and his wife Ann Murphy, friends of the Bushes, paid their respects to Mrs. Bush by thanking her for her inspiration throughout the years.
"She was feisty, she was fun, and as soon as she embraced you, she made you family. Those were the three Fs," Dr. Murphy said.
Mark Kelly and his wife, former Congresswoman Gabrielle Giffords, also paid their respects.
Barbara Bush touched so many lives through her charitable works over the years and inspired others.
That includes Jim "Mattress Mack" McIngvale, who, like so many many others, came out to honor and celebrate the life of Mrs. Bush.
"She's the First Lady of Texas, First Lady of Houston. There will always be a place in my heart and in houstonians for Barbara Bush," Mack said.
Mrs. Bush was known for being thoughtful and caring. Pastor of Second Baptist Church Ed Young shared a time the Bush's came to visit him and his late wife Jo Beth Young at the hospital. He said Mrs. Bush would hold his wife's hand day after day.
Mrs. Young died at 80 years old on September 17, 2017.
Christian singer Amy Grant was friends with Mrs. Bush for over 30 years. She says her thoughts and prayers are the Bush family.
"She was an incredible woman. A strong and amazing woman," Grant said.
PHOTOS: Friends and family of Barbara Bush arrive to pay their respects to the former First Lady