The service by Hope Memorial Church was held in Manor Park in Aldershot on Sunday evening came after the infant's body was found in bushes in the same park two days before.
Named by police only as "Baby M", office have not yet confirmed further details about the baby girl but her mother is being urged to contact Hampshire Police or go to a hospital.
Pls RT: #Aldershot CI Debbie Brooks' appeal to mother of baby whose body was found in Manor Park to come forward. pic.twitter.com/SfAOmBZGki
— Hampshire Police (@HantsPolice) May 20, 2017
In a statement, the force said: "We're in a position to confirm that the body of a baby found in Manor Park on Friday (19 May) was a girl.
"We're still concerned for the welfare of Baby M's mother, who may need urgent medical attention. We would urge her to call 101 or to go a hospital."
It is unknown how long the body was in the park before it was discovered.
Anyone with information relating to the case is asked to call 101 quoting reference '44170188442', or contact Crimestoppers anonymously.