Ryan was present as his father James McGowan was sentenced to a minimum of 18 years behind bars by the High Court of Glasgow for stabbing Owen Brannigan to death in North Lanarkshire, Scotland in 1999.
McGowan was convicted of Brannigan's murder at a trial in the High Court of Edinburgh in February, BBC reports.
The court heard that McGowan killed Brannigan out of revenge for a rape he believed was committed against a family member and fled to Australia the next day.
The 57-year-old denied the attack, which took place after he traveled to Scotland for his mother's funeral.
While attending the funeral, McGowan stabbed Brannigan in the neck 11 times.
McGowan went into hiding in Adelaide where he raised his two sons until he confessed to the murder on a suicide hotline after the breakdown of his marriage.
Australian police arrested McGowan in 2013 before he was transferred to Scotland Yard in 2016 after a lengthy extradition process.
Ryan McGowan, who has 18 Socceroos caps, exchanged a brief smile with his father as the 57-year-old was led to the cells.
Ryan, 27, recently joined Chinese Super League club Guizhou Hengfeng Zhicheng, while his younger brother Dylan, 25, has been at A-League side Adelaide United since 2014.
Ryan was named in Australia's 2014 FIFA World Cup squad and was the player who provided the assist to Tim Cahill's stunning goal in Australia 3–2 loss to the Netherlands.