Todd McCarthy of Variety said the film is "as broad and obvious as it could be, but delivers on its own terms thanks to sparky chemistry between its sunny blond stars, Owen Wilson and Jennifer Aniston, and the unabashed emotion-milking of the final reel. Fox has a winner here, likely to be irresistible to almost everyone but cats ... Animated and emotionally accessible, Aniston comes off better here than in most of her feature films, and Wilson spars well with her, even if, in the film's weaker moments, he shows he's on less certain ground with earnest material than he is with straight-faced impertinence."
Kirk Honeycutt of The Hollywood Reporter observed that "seldom does a studio release feature so little drama - and not much comedy either, other than when the dog clowns around ... [W]hatever Marley wants to be about - the challenges of marriage or the balancing act between career and family - gets subsumed by pet tricks. Dog lovers won't care, and that basically is the audience for the film. From Fox's standpoint, it may be enough ... Marley & Me is a warm and fuzzy family movie, but you do wish that at least once someone would upstage the dog."
Roger Ebert of the Chicago Sun-Times called the film "a cheerful family movie" and added, "Wilson and Aniston demonstrate why they are gifted comic actors. They have a relationship that's not too sitcomish, not too sentimental, mostly smart and realistic."
Owen Gleiberman of Entertainment Weekly graded the film A-, calling it "the single most endearing and authentic movie about the human–canine connection in decades. As directed by David Frankel, though, it's also something more: a disarmingly enjoyable, wholehearted comic vision of the happy messiness of family life."
Steve Persall of the St. Petersburg Times graded the film B and commented, "Marley & Me practically leaps at viewers like a pound puppy seeking affection, and darn if it doesn't deserve some ... Things could get mushier or sillier, but Frankel and screenwriters Scott Frank and Don Roos — who usually handle grittier material — decline to play the easy, crowd-pleasing game. Their faith in Grogan's simple tale of loyalty among people and pets is unique, and it pays off ... [It] isn't extraordinary cinema, but it relates to everyday people in the audience in a way that few movies do without being dull."
Walter Addiego of the San Francisco Chronicle said, "This love letter to man's best friend will make dog fanciers roll over and do tricks. It's so warmhearted, you'll want to run out and hug the nearest big, sloppy mutt."
Carrie Rickey of the Philadelphia Inquirer awarded the film three out of four stars and commented, "Marley and Me operates on the assumption that happiness is a warm tongue bath. And those who endorse this belief will enjoy this shaggy dog story ... The anecdotal structure does not make for a gripping movie. For one thing, there's no conflict, unless you count the tension between a guy and his untrainable pooch. Yet Marley boasts animal magnetism ... Mawkish? Sometimes. But often very funny and occasionally very moving."
Betsy Sharkey of the Los Angeles Times called it "an imperfect, messy and sometimes trying film that has moments of genuine sweetness and humor sprinkled in between the saccharine and the sadness."
New Game Plus, a new review site gave the film an 8/10 stating that "While you can see the ending coming from a mile away, you enjoy the journey, and what a journey it is.