In 2016, Am was included in a South Africa 'A' squad that played a two-match series against a touring England Saxons team.[8] He came on as a replacement in their first match in Bloemfontein,[9] but ended on the losing side as the visitors ran out 32-24 winners.[10] He was promoted to the starting line-up for the second match of the series, a 26-29 defeat to the Saxons in George.
Am was named as Captain of South Africa 'A' for the warm-up game against the British and Irish Lions on July 14, 2021. He proudly led the South African team to a successful win against the visitors. Lukhanyo scored one of the two converted tries in the exhibition match.
Am was included in the South African squad for the 2017 end-of-year rugby union internationals.
He has had a prolific impact on the backline of the Springboks, partnering well with Damian De Allende and causing havoc for opposition teams. He was very instrumental in the lead up games to the 2019 Rugby Championship campaign. Am was part of the Springboks team that lifted the coveted 2019 Rugby Championship trophy. He has also been named on several games the vice-captain to Siya Kolisi, as further proof of his instrumental impact on the team.
Am was named in South Africa's squad for the 2019 Rugby World Cup. South Africa won the tournament, defeating England in the final, where the Springboks won the match convincingly with a runaway score of 32-12. Who can ever forget the amazing run and wicked pass Am gave Makazole Mapimpi, which led to a memorable and historic Springboks first finals try in Rugby World Cups. All previous Springboks World Cup finals were won without tries.[13] Am played a central role in the Springboks' 2019 World Cup campaign, featuring in six out of seven matches.
Am played all the games against the visiting British and Irish Lions, having successfully led South Africa 'A' as captain in the warmup match. The Springboks eventually won the series and this was a further crowning of Am and his centre partner Damian De Allende, when they were applauded for their escapades and well regarded as the best center pairing in World Rugby.
Although Am did not initially make South Africa's 2023 Rugby World Cup squad due to injury suffered in the last game against the Argentinian team, he was later called up to the campaign in France for the injured Makazole Mapimpi