Kovačić began his professional career with Dinamo Zagreb at the age of 16, with whom he won two consecutive Prva HNL titles, before joining Inter Milan in 2013.

Born in Austria, Kovačić played for Croatia at multiple youth levels before making his debut for the senior national team in 2013.

[6][8] Kovačić suffered a serious injury in 2009 in which his leg was broken, but he returned to the pitch after a lengthy recovery on 31 May 2010, appearing in the last match of the Croatian under-17 academy league, in a friendly 5–0 win against RNK Split under-17s.

[11] Kovačić had his professional league debut in the 2010–11 Prva HNL away match against Hrvatski Dragovoljac on 20 November 2010, in which he scored Dinamo's fourth goal in their 6–0 win.

He finished his first European season with Dinamo by scoring a goal against Lyon in the last game of the group stage in Zagreb and thus became the second youngest ever scorer in the Champions League.

[16] In the beginning of 2012–13 season, he suffered a metatarsal bone injury that caused him to miss several games on the club's qualifying road to another Champions League.

Kovačić played in all six Dinamo Zagreb's matches in the 2012–13 Champions League group stage, against Porto, Paris Saint-Germain and Dynamo Kyiv.

In October 2012, he was nominated for Golden Boy, an award given by sports journalists to a young player from Europe perceived to have been the most impressive during a season.

[17] During the season's winter break, Dinamo's board threw away the speculations about Kovačić leaving the club in the near future by saying they are building a new team around him and another rising star, Alen Halilović.

[20] On 14 February, Kovačić made his European debut before the home crowd at San Siro in a 2012–13 UEFA Europa League match against CFR Cluj.

He provided the winning assist for Rodrigo Palacio, who made it 2–0 for Inter, impressing the crowd with his performance, and was given standing ovations while being substituted off in the 89th minute.

[24] Kovačić was a starter in Inter's next Serie A match, a 0–2 away win against Sampdoria, as well as in their surprising 3–4 loss to Atalanta at San Siro, where he provided an assist for Ricky Álvarez's goal.

[35][36][37] He started the season in strong fashion, scoring a hat-trick in the second leg of the Europa League play-off round against Stjarnan on 28 August.

[49] Four days after his presentation, he made his debut as a 70th-minute substitute for Isco as Real Madrid began the 2015–16 La Liga with a 0–0 draw away to Sporting Gijón.

[citation needed] In the opening months of the season, he was used quite regularly by then Real Madrid manager Rafael Benítez, playing in almost every midfield position there is – sometimes central, sometimes wide, sometimes further forward.

[60] On 29 May 2019, he started in the 2019 Europa League final in Baku, playing until 78th minute when he was substituted off for Ross Barkley, as Chelsea beat Arsenal 4–1.

[76][77][78] Ahead of the second leg of the 2020–21 Champions League quarter-finals against Porto, Kovačić sustained a tendon injury and was forced to miss the semi-final tie against his former club Real Madrid, which Chelsea won 3–1 on aggregate.

[95][96] On 27 June 2023, fellow Premier League club Manchester City announced the signing of Kovačić on a four-year deal.

[98] On 6 August, he made his competitive debut for the club against Arsenal in the FA Community Shield, which City lost 4–1 on penalties after a 1–1 draw.

On 19 December 2023, Kovačić scored his first goal for Manchester City in a 3–0 FIFA Club World Cup semi-final win against Urawa Red Diamonds.

[citation needed] In August 2012, Kovačić received his first competitive call-up for the Croatian senior team match against Switzerland, but did not play because of injury.

He made his senior debut in a qualification match against Serbia on 22 March, playing as a central midfielder alongside Luka Modrić, instead of a regular team starter, Ognjen Vukojević.

His third match of the campaign came in June, when Croatia faced Scotland in Zagreb and suffered a frustrating defeat as they were unable to score despite a string of good chances.

[110] On 22 June, Kovačić provided an assist to his teammate Ivan Rakitić as he scored Croatia's third goal in a 3–0 win over Argentina in their second group stage match of the tournament.

[112] Kovačić appeared in Croatia's 2018–19 UEFA Nations League A matches against Spain away and England home, that ended up as 6–0 defeat and a goalless draw, respectively.

[116][117] In a return leg on 13 October, in the build-up to Wales' goal, Kovačić was controversially injured by Ben Davies as the match ended up as a 1–1 draw.

[144][148][149] He lies in the 97th percentile for players dribbled past per 90 minutes,[148] preferring to charge beyond defenders in order to create chances from advanced positions.

[147][149] Kovačić is highly proficient at what is known as "press resistance", the capacity to wriggle out of trouble when under pressure from one or more opposition players, often via a dribble or clever pass around the corner.

[150] His compatriot, Zvonimir Boban, who played for Milan for over a decade, in an interview with Sky Italia in 2013 said, "He has talents that could make him even better than me, he is an incredibly serious professional for someone his age.

[153] Kovačić was born in Linz, Austria, to Bosnian Croat parents Stipo and Ružica who had moved there from Zabrđe[154] ahead of the Yugoslav Wars.