Houston, married to a Vietnamese woman in Da Nang city, had travelled to a number of epidemic-hit countries before returning to Da Nang on March 14.
As soon as he landed at Da Nang International Airport, he was placed in quarantine and later tests showed he had contracted the virus.
Dr Le Duc Nhan, director of Da Nang Hospital, said the patient remained in stable health condition after admission to hospital. X-ray images of his lungs, kidneys and livers showed they were operating normally.
Being discharged from hospital on April 3, Houston said Vietnam has done a good job concerning the isolation work to ensure the virus could not spread to the wider community.
He also thanked Vietnamese doctors for saving his life and protecting his family from the coronavirus.
Houston is the fourth COVID-19 patient having received discharge from hospital in Da Nang.
Earlier, two British citizens and a Vietnamese saleswoman had also been released from hospital after making a full recovery.