Kylian Mbappé and Federico Valverde struck inside the opening 23 minutes to give José Mourinho’s side a commanding advantage, but Inter responded after the interval through Carlos Augusto and pushed strongly for an equaliser.
Real Madrid ultimately held on, with Thibaut Courtois producing a superb performance in goal to secure three important points for the Spanish giants.
Mbappé Punishes Inter Error
Inter had enjoyed a positive opening and controlled significant periods of possession, but their first major defensive mistake proved costly.
In the 14th minute, Inter defender Yann Bisseck slipped while attempting to deal with the ball under pressure.
Brahim Díaz immediately capitalised on the error, releasing Mbappé, who raced through before calmly finishing past goalkeeper Josep Martínez to put Madrid 1–0 ahead.
The goal was another landmark moment for Mbappé in the competition. His strike took him to 71 Champions League goals, moving him level with Real Madrid legend Raúl González among the competition's leading scorers.
Valverde Doubles Madrid's Lead
Inter continued to see plenty of the ball but were punished again for another costly mistake.
Just nine minutes after Mbappé's opener, goalkeeper Josep Martínez attempted to evade Federico Valverde inside his own penalty area.
The Uruguayan midfielder won possession and finished into the empty net to make it 2–0 in the 23rd minute.
It was a remarkable turnaround for Madrid, who had been under pressure during portions of the opening half but found themselves two goals ahead after exploiting two defensive errors.
Inter Fight Back After Half-Time
Despite trailing by two goals, Inter refused to collapse.
The Italian side controlled large stretches of the match and continued to create opportunities around the Madrid penalty area.
Real Madrid, meanwhile, looked dangerous on the counter but were unable to add a third goal that would have killed off the contest.
Inter's persistence eventually paid off when Carlos Augusto reduced the deficit, finishing after an assist from Lautaro Martínez.
The goal gave Inter renewed belief and transformed the final stages into a tense contest.
Courtois Keeps Real Madrid Ahead
As Inter pushed for an equaliser, Courtois became increasingly important.
The Belgian goalkeeper produced several crucial saves, including a spectacular double intervention in the second half that denied Inter when they appeared certain to score.
Inter ultimately finished with around 70 per cent possession and 12 shots, compared with just three attempts for Madrid, underlining how much pressure the home side faced despite leading for most of the game.
Madrid's ability to survive that pressure proved decisive.
Mourinho Wins Champions League Return
The victory marked a winning return to Champions League football for José Mourinho in his second spell as Real Madrid manager.
Mourinho had admitted before the game that he felt no additional pressure to win the competition, despite the Champions League being the major trophy he failed to secure during his first spell at the club.
His team, however, began the new European campaign with three points against one of the competition's traditional heavyweights.
The victory also provides some relief after Madrid's recent 1–0 defeat to Real Betis, their first setback of the season.
Vinícius Jr Receives Mixed Reaction
One of the talking points from the Bernabéu was Vinícius Júnior's second-half performance.
The Brazilian worked hard defensively but did not register a goal or assist before being substituted in the 87th minute.
Some sections of the Bernabéu crowd booed the forward as he left the pitch, while Mourinho publicly backed his player, praising his effort and insisting that his work deserved respect.
Real Madrid Start With Three Points
The 2–1 victory gives Real Madrid an ideal start to the Champions League league phase, although their performance also highlighted areas Mourinho will want to improve.
Inter demonstrated that they could trouble Madrid for long periods, but two defensive errors in the first half proved too costly.
For Real Madrid, however, the immediate objective has been achieved: three points, two goals and a valuable opening victory against Inter Milan.
Mbappé provided the early spark, Valverde added the second and Courtois ensured Inter's late pressure did not change the outcome.