In comments published by the Mail today, Susan Manning said he should know she considered him her "Superman."
"Never give up hope, son," she was quoted as saying. "I know I may never see you again, but I know you will be free one day. I pray it is soon."
Susan Manning, a 59-year-old from Wales, had not given an interview in years.
Manning's parents have largely stayed out of the spotlight since transparency group WikiLeaks began publishing the documents leaked to it by the 25-year-old Army private.
The soldier was convicted last month on a slew of charges, including Espionage Act violations, but was acquitted of the most serious charge, aiding the enemy. Sentencing hearings in his case are expected to resume tomorrow.