Ronaldo scores first goal this season as Man Utd stroll in Europa League
Stay tuned with 24 News HD Android App
But the Portugal star will be relieved to have got on the scoresheet, after Jadon Sancho put United ahead with a well-timed response on the day he was left out of the England squad.
United lost their opening Group E match 1-0 against Real Sociedad last Thursday in a match overshadowed by the death of Queen Elizabeth II.
That gave Erik ten Hag's side no margin for error in Chisinau and they were up to the task against a Sheriff side who enjoyed a stunning 2-1 victory at Real Madrid in the Champions League group stage last season.
United's first trip to the far-flung outpost of Moldova served as a painful reminder of their diminished status following last season's failure to qualify for the Champions League.
Sheriff's home ground in Transnistria was deemed too dangerous by UEFA due to the war in neighbouring Ukraine, forcing the match to be moved 40 miles to the drab surroundings of the tiny Zimbru Stadium in Chisinau.
David De Gea's complaint before the match that United "should be playing Champions League" contained a hint of arrogance, but Ten Hag acknowledged Sheriff were "a serious and decent opponent".
Ten Hag named a strong side and Sancho, one of five changes, struck with United's first meaningful attack in the 17th minute.
- Sancho strikes -
Just hours after learning he was not in the England squad for their Nations League games, Sancho reminded Three Lions boss Gareth Southgate of his quality.
Taking Christian Eriksen's pass in his stride, Sancho cleverly switched direction inside the Sheriff area, giving himself room to plant a cool finish into the bottom corner from 12 yards.
After a disappointing first campaign following his move from Borussia Dortmund, Sancho is starting to flourish and he celebrated his third goal this season by holding up a shin pad -- one of a personalised pair given to the 22-year-old by a young fan recently.
Sancho was denied a second goal when Stjepan Radeljic cleared his shot off the line, but United still doubled their lead in the 39th minute.
Diogo Dalot was brought down by Patrick Kpozo and Ronaldo stepped up to stroke home the spot-kick with ease.
United remain three points behind group leaders Real Sociedad, who won 2-1 against Omonia Nicosia.
Sociedad took the lead through Ander Guevara in the 30th minute and former Crystal Palace striker Alexander Sorloth bagged the 80th minute winner after Bruno equalised eight minutes earlier.
Ferencvaros won 1-0 at Monaco thanks to Balint Vecsei's 79th minute goal as the Hungarians moved to the top of Group H, with Trabzonspor beating Red Star Belgrade 2-1.
Freiburg made it two successive Group G wins as Michael Gregoritsch scored twice in a 3-0 stroll at Olympiacos, while Qarabag beat Nantes 3-0.
In Group F, Midtjylland powered to a stunning 5-1 rout of Lazio.
Paulinho, Sory Kaba, Evander, Gustav Isaksen and Erik Sviatchenko all scored for the Danish club, with Sergej Milinkovic-Savic's reply no consolation for the embarrassed Serie A side.
Feyenoord top the group after Iran winger Alireza Jahanbakhsh hit a hat-trick in their 6-0 demolition of Sturm Graz.