Aftab Bahadur, sentenced to death when he was just 15, has been hanged after 23 years on death row.
He was sentenced to death in 1992 after being accused of three murders which his lawyers say he was tortured into admitting.
The human rights group Reprieve says two witnesses who implicated Bahadur had since recanted saying they too were tortured.
In an essay published a day before his hanging Bahadur maintained his innocence.
Pakistan lifted a moratorium on executions last year after gunmen attacked a school, killing 153 people, most of them students.