Drmić is a Swiss international, having played at under-19, under-21 and senior level.
He was a member of Switzerland's squad at the 2012 Summer Olympics, and came on as a substitute in the last two matches as the team were eliminated in last place in Group B.
On 11 September 2012, Drmić won his first cap for the Switzerland senior team in a 2–0 2014 FIFA World Cup qualifying win over Albania.
He scored his first two international goals in a 2–2 draw with Croatia on 6 March 2014.

On 13 May 2014, Drmić was named in Switzerland's squad for the 2014 World Cup.
He scored the only goal of the match in the 83rd minute from Blerim Džemaili's assist as Switzerland beat Jamaica in a warm-up match for the tournament on 30 May. In the first match of the tournament, a 2–1 win over Ecuador, he had a goal ruled out for offside and was substituted for Haris Seferović, who scored the winning goal.
Drmić was dropped for Seferović for the second match, a 5–2 defeat to France, but returned and set up two of Xherdan Shaqiri's three goals in the 3–0 win over Honduras in the last group match in Manaus, which saw Switzerland advance to the knockout stage as group runners-up.

Drmić scored his first competitive goal for Switzerland on 14 June 2015, equalising in a 2–1 away victory over Lithuania in UEFA Euro 2016 qualifying.
On 5 September, he came on in the 64th minute for Blerim Džemaili, and scored twice as the Swiss came from 0–2 down to defeat Slovenia 3–2 in a qualifier in Basel.
After having knee surgery in March, he missed the final tournament.

In qualification for the 2018 World Cup, Drmić scored once, the sole goal of a victory over Latvia at the Stade de Genève on 25 March 2017.
It was his first goal in any match since February 2016, heading an Admir Mehmedi cross two minutes after coming on in place of Gelson Fernandes.
Manager Vladimir Petković named him for the squad to compete in the finals in Russia.
In the final group game against Costa Rica in Nizhny Novgorod, he came on as a late substitute for Mario Gavranović and scored in a 2–2 draw that ensured passage to the last 16.

At the 2018–19 Nations League in Portugal, Drmić was the only player to miss in the third-place penalty shootout against England, with Jordan Pickford saving from him in sudden death.
Drmić is a Swiss international, having played at under-19, under-21 and senior level. He was a member of Switzerland's squad at the 2012 Summer Olympics, and came on as a substitute in the last two matches as the team were eliminated in last place in Group B.
On 11 September 2012, Drmić won his first cap for the Switzerland senior team in a 2–0 2014 FIFA World Cup qualifying win over Albania. He scored his first two international goals in a 2–2 draw with Croatia on 6 March 2014.
On 13 May 2014, Drmić was named in Switzerland's squad for the 2014 World Cup. He scored the only goal of the match in the 83rd minute from Blerim Džemaili's assist as Switzerland beat Jamaica in a warm-up match for the tournament on 30 May. In the first match of the tournament, a 2–1 win over Ecuador, he had a goal ruled out for offside and was substituted for Haris Seferović, who scored the winning goal. Drmić was dropped for Seferović for the second match, a 5–2 defeat to France, but returned and set up two of Xherdan Shaqiri's three goals in the 3–0 win over Honduras in the last group match in Manaus, which saw Switzerland advance to the knockout stage as group runners-up.
Drmić scored his first competitive goal for Switzerland on 14 June 2015, equalising in a 2–1 away victory over Lithuania in UEFA Euro 2016 qualifying. On 5 September, he came on in the 64th minute for Blerim Džemaili, and scored twice as the Swiss came from 0–2 down to defeat Slovenia 3–2 in a qualifier in Basel. After having knee surgery in March, he missed the final tournament.
In qualification for the 2018 World Cup, Drmić scored once, the sole goal of a victory over Latvia at the Stade de Genève on 25 March 2017. It was his first goal in any match since February 2016, heading an Admir Mehmedi cross two minutes after coming on in place of Gelson Fernandes. Manager Vladimir Petković named him for the squad to compete in the finals in Russia. In the final group game against Costa Rica in Nizhny Novgorod, he came on as a late substitute for Mario Gavranović and scored in a 2–2 draw that ensured passage to the last 16.
At the 2018–19 Nations League in Portugal, Drmić was the only player to miss in the third-place penalty shootout against England, with Jordan Pickford saving from him in sudden death.
Josip Drmić