The couple first met the 18-month-old in 2015, while Lauren was visiting Willa's home in Uganda on a trip with 147 Million Orphans, reported E! Online.
Rhett, 27, also took to Instagram to share the happy news with fans and share a picture of him along with his wife and Willa.
"Everyone meet Willa Gray Akins! I can't believe our daughter is finally home. We have been in this adoption process for what seems like forever and are just so filled with joy that we are all finally home together!