Kompany played in eight league matches for Manchester City during the first portion of 2017–18, suffering further strains during the period, before withdrawing minutes into an away fixture against Newcastle on 27 December; Guardiola's responses in the press conferences suggested he was losing patience with the situation. He returned to the team on 3 February 2018, completing the 90 minutes of a 1–1 draw away to Burnley while Aymeric Laporte, the club's new record signing in the same position, remained on the bench throughout. On 25 February, he scored Manchester City's second goal of a 3–0 victory over Arsenal in the 2018 EFL Cup Final, and was named man of the match. he eventually managed 17 league starts as Manchester City won the title with a record 100 points.
At the 2018 FIFA World Cup in Russia, Kompany featured in five of his nation's seven matches, playing every minute in the knockout phase as they advanced to the semi-finals before losing to eventual champions France, overcoming England to finish third, their highest ever placing in the competition.
Kompany's father, Pierre, is a Congolese immigrant to Belgium and serves as his agent. In October 2018, Pierre was elected the mayor of Ganshoren, making him the first black mayor in Belgium. His late mother, Jocelyne, was Belgian. His brother, François Kompany, plays for Roeselare, having previously had spells at Germinal Beerschot and Macclesfield Town. Kompany also has an older sister. Among his friends are former Chelsea goalkeeper Yves Ma-Kalambay and former Manchester United defender Floribert N'Galula, both of whom he consulted about his move to England before joining Manchester City.
Kompany has a number of pastimes and interests which keep him occupied outside of football. He has an interest in politics and graduated with an MBA at Manchester Business School in 2018 after several years of study. Kompany has been characterized as "erudite" and "eloquent".