The former marine who has served more than half of his sentence will be free to return to the United States following the pardon.
The Philippines has so far detected 2,311 cases and reported 96 deaths.
President Rodrigo Duterte came to power in May 2016, riding on the wave of a harsh anti-drug rhetoric.
Amnesty names US President Donald Trump a "human rights offender" alongside Rodrigo Duterte, Vladimir Putin and Abdel Fatah al-Sisi.
Philippines president recently stirred up a controversy after asking his troops to shoot female communist rebels in their vaginas.
"Shoot female rebels in their vaginas," President Rodrigo Duterte tells Armed Forces of the Philippines (AFP).
Philippines' president says his country is a dictatorship but claims that that is just what it needs.
Philippines President Rodrigo Duterte under preliminary investigation at International Criminal Court for crimes against humanity in war on drugs.
The Philippines president hits back at the European Union bloc and explains how he does not want to visit Brussels.
Philippine president Rodrigo Duterte ordered the destruction of 20 sports cars worth $1.2m (£860,000), which had been smuggled into the country illegally.
Even well-known people have often blamed victims for sexual assaults, sparking widespread outrage.
Philippines President Rodrigo Duterte feels "pity" about the situation Myanmar's leader Aung San Suu Kyi finds herself in regarding the Rohingya criticism.
Philippines President Rodrigo Duterte's sexist joke has angered women's rights groups, with some of them saying the remarks are "extremely worrying".
Philippines president Duterte has repeatedly made it clear that he does want to stay in power beyond his term when it ends in 2022.
Children as young as three spend their days sitting in soot and breathing in coal dust and toxic smoke to make charcoal out of wood scavenged from rubbish dumps.
One of Asia's most colourful leaders did not mince his words this year delivering expletive-laden remarks.
The Philippines president said rape victims in "his time" used to be beautiful and "worth dying for".
The Philippines president says he supports gay marriages and he is even ready to rewrite laws to legalise same-sex unions.
Storm Kai-tak pounds Philippines, leaves over 30 dead and dozens missing in island province of Biliran after triggering severe flooding and landslides.
Australian photojournalist Ted McDonnell documents life in Happyland, a ramshackle collection of shelters built around a rubbish dump outside Manila.
When asked whether he would impose a nationwide martial law to combat terror, the Phillipines president said "all options are on table".
The Philippines president argued martial law powers are necessary to root out the extremists who have been regrouping after the military campaign.
The Philippines president warns the industrialisation and urbanisation should move beyond the capital as Manila will soon hit a saturation point.
The Philippines president earlier ordered the police forces to stand down from playing an active role in the anti-drug crackdown due to deaths of teenage suspects.
Rights group Amnesty International earlier said there have been serious human rights violations committed by Filipino soldiers in Marawi.
Duterte on Trudeau's concerns: 'I only answer to the Filipino, I won't answer to any other b******t'
The Philippines president attacks the Canadian prime minister for raising the touchy issue of human rights allegations during their brief exchange.
The US president said his gruelling five-nation tour has been "tremendously successful" touting unconfrimed dollar figures.
Philippines President Rodrigo Duterte and US President Donald Trump met officially on the sidelines of the 31st Association of Southeast Asian Nations Summit.
US President Donald Trump has offered to moderate talks between the multiple claimants in the South China Sea dispute.
The Philippines controversial president Rodrigo Duterte said he stabbed a person to death as a teenager.