Barca's 1-0 win over Athletic Bilbao 24 hours earlier had put the pressure back on Zinedine Zidane's men, but Vinicius' goal after 19 minutes steadied any nerves within the home side.
Mallorca, who sit third from bottom of the table, gave a spirited account of themselves but rarely looked likely to claim a share of the spoils despite Madrid having made four changes from the 2-1 win at Real Sociedad on Sunday.
Zidane elected to start Vinicius, Eden Hazard and Gareth Bale in support of Karim Benzema but it was captain Sergio Ramos who made the win safe with an exceptional free-kick early in the second half.
5 - Vinícius Júnior has been involved in five goals in his last seven starts for @realmadriden in all competitions (3 goals, 2 assists), winning a penalty in the last matchday against Real Sociedad. Impact. pic.twitter.com/oFh7c1sATY— OptaJose (@OptaJose) June 24, 2020
Vinicius might have been a surprise starter but he justified Zidane's call 19 minutes in, steering a finish high past Manolo Reina after a clever reverse pass from Luka Modric.
The Brazilian hit the bar with a lob from a Karim Benzema throughball four minutes later, but it was Mallorca who threatened more as the half went on, even though Thibaut Courtois' goal was largely well protected.
Madrid took control with a second goal 10 minutes into the second half, Ramos curling a fine free-kick into the top-left corner from just outside the penalty area.
Mallorca did not lose heart at least and threatened through Madrid loanee Takefusa Kubo, who saw a shot hit the side-netting after one impressive run through the box.
The visitors remain three points from safety and at serious risk of relegation, but they did at least make a moment of LaLiga history when Luka Romero came off the bench to become the youngest player ever to play in the competition at the age of 15 years and 219 days.
1 - Aged 15 years and 219 days, Mallorca's Luka Romero becomes the youngest player to ever play a @LaLigaEN game, beating Sansón's record for Celta de Vigo in December 1939 (15 years and 255 days). Kid.— OptaJose (@OptaJose) June 24, 2020
What does it mean? Zidane's side taking shape for double charge
Madrid are back on top of the table above Barcelona on their head-to-head record and appear to be in good shape after the lockdown.
Zidane changed the system and personnel but was still rewarded with a strong performance. That sort of adaptability bodes well for their title challenge, and the return of the Champions League in August.
Vinicius on a mission
Having gone through a difficult spell this season, Vinicius looks determined to become a mainstay in Zidane's plans.
He scored one good goal, almost got a second and pressed across the front in the second half to keep the Mallorca defence worried.
No lucky break for Bale
Bale got out of Vincius' way to let his team-mate open the scoring and it was his most useful contribution of the game.
It was more a disinterested performance than a poor one, but certainly was not one to make his coach think he merits a regular place in the first XI.
Madrid head to Espanyol on Sunday, with Mallorca facing Athletic Bilbao at San Mames a day earlier.