Carlo Ancelotti's side made a bright start at the Estadio de los Juegos Mediterraneos, with Ronaldo needing less than three minutes to break the deadlock.
There remained only one goal in it until after the hour mark, but then the floodgates opened and further strikes from Karim Benzema, Gareth Bale, Isco and Alvaro Morata sealed the rout, with the only worry for the capital club the fact Ronaldo had to come off at the start of the second half due to injury.
Almeria, who headed into the game in the relegation zone but on a run of three straight wins, brought in Jose Antonio Verza and Suso for Marcos Tebar and Fernando Soriano.
Real showed three changes from the side which thrashed Real Sociedad 5-1 last time out, with Isco, Asier Illarramendi and Sergio Ramos starting in place of Luka Modric, Sami Khedira and Raphael Varane.
Ancelotti's side, having seen arch rivals Barca consolidate top spot with a 4-0 win over Granada in the early kick-off to move provisionally nine points clear, were out of the blocks quickly in Andalusia.
Ronaldo, fresh from almost single-handedly getting Portugal to the World Cup finals with a brilliant hat-trick in the midweek play-off second leg against Sweden, stretched out his left foot to connect with Isco's cross from the right and divert the ball past Esteban.
That was the former Manchester United man's 35th goal in his last 25 appearances, and he did not look content to settle for that.
Another piledriver in the fifth minute was parried by Esteban, who then also saved the follow-up from Benzema.
The 38-year-old Almeria goalkeeper again had to be alert just after the half-hour mark after Ronaldo burst through the middle, riding three challenges in the process, before unleashing a shot which had looked destined for the bottom-left corner.
Isco and Ronaldo had further efforts blocked and Daniel Carvajal volleyed over, while Bale went close to a spectacular goal when he took the ball on his chest 40 yards out and volleyed over the bar as he looked to catch Esteban off his line.
Carvajal surged into the area early in the second half and whipped in a vicious cross-shot which looked to be heading into the far corner before Esteban's fingertips deflected it wide, although a goal-kick was given - much to the Real right-back's dismay.
Carvajal teed up Bale with a low cross soon after, which the Welshman somehow spooned way over the bar from close range.
Ronaldo's evening came to a premature end early in the second half, when he signalled to the bench that he had picked up a knock and wanted to come off.
Diego Lopez had had little to do in the Real Madrid goal but stayed alert to keep out Suso's fierce drive 10 minutes after the restart.
Benzema, back at the other end, wasted no time in taking centre-stage up front with a superb second goal in the 61st minute. The France forward took on a pass from Ronaldo's replacement Jese on the edge of the box, gave himself some space with his first touch and then despatched a fine left-footed shot past Esteban.
That turned out to be Benzema's last contribution before he was replaced by Morata.
Bale passed up another chance to get on the scoresheet when he headed wide from Isco's cross midway through the second period, but was finally rewarded for his endeavours six minutes later.
Isco was again a key figure in the build-up, with Sebastian Dubarbier attempting to deal with his through-pass but succeeding only in running into Bale, who gleefully tucked away with his left foot for his third goal in La Liga.
Isco added gloss to the scoreline with a goal of his own moments later, striking the ball through the legs of substitute Tebar and into the bottom-left corner.
And, as if Almeria's winning streak had no been ended emphatically enough, Morata then sprung the offside trap 10 minutes from time and lifted a cheeky dink over Esteban.