Marv first appears during a scene at night alongside with his partner Harry, sitting in the passenger seat of the van. Harry, who is revealed to be a burglar who had disguised himself as a cop earlier in the film, gloats about how the residents of the neighborhood informed him when they were going to leave for the holiday. It was the McCallisters' house that came to be the number one target, the "Silver Tuna", and the yard both burglars decide to pull the van in on first. Harry and Marv both exit the van having with their crowbars. Unknown to both burglars however, Kevin, who is home alone, is in the living room becoming scared when he sees their shadows from the windows as they head toward the basement. The burglars try to pry open the basement door with their crowbars. Kevin immediately runs through the house turning on light switches to deter the burglars, which he does so after turning on the light in the basement. Harry and Marv are confused, as they were previously informed that the McCallisters were leaving for Paris that morning, along with yet knowing that only Kevin was still in the house, and at that both burglars flee.
Harry and Marv are inside the Murphys' house. Kevin passes by while heading to the store and sees the van parked in front of the Murphys' garage wondering if the family had left or not. Harry is crouched next to the Christmas tree, playing with unwrapped presents, while Marv is recklessly and loudly shoving and throwing items off into a large leathery bag with his crowbar. Marv comes over to one of the phones in the house and pauses when it rings. The answering machine comes on, and he picks it up, quietly listening to a message by Peter McCallister sent to the Murphys. It confirms that the McCallister family (except for Kevin) are in fact in Paris, of which Marv calls out to Harry saying that he's right, that the McCallisters are not home. While the message was for the concern of Kevin, it appears Peter only tells the Murphys to call, giving them the country code, area code, and part of the phone number of the current location where he and his family were at (though we do not get to really hear the entire message because of Marv speaking over). Thus, with Marv being only interested in the message confirming the family's absence rather than knowing why they were leaving a message, it was not given away that a McCallister kid was home alone.
Later, Marv is seen in the Murphy's kitchen clogging up the drains of the kitchen sink and turning on the faucet leaving it running. As he heads out of the house carrying a bag of merchandise with him, Harry sees the smirk on Marv's face and knows about what had been done in the kitchen. Harry expresses disapproval calling it sick, but Marv claims the deed to be their calling card for as he puts it "All the great ones leave their mark. We're the Wet Bandits". Harry calls Marv sick and the two start arguing. Meanwhile, Kevin, who has returned from the store after evading a police officer for leaving the store with a toothbrush without paying, walks by in front of the driveway and does not notice the van pulling out. Unfortunately, Harry and Marv who are still busy arguing, do not see Kevin walking by. Luckily, Marv sees Kevin first and tells Harry to watch out, and Harry immediately hits the brakes. Kevin then sees the vehicle and helplessly stands screaming as it stops only an inch away from his face.
As Kevin walks away, Harry immediately rolls down his window, and both men briefly hint about safety precaution to the boy before Harry smiles and wishes him a "Merry Christmas". He and Harry then follow Kevin, but lose him at the church.
Later, they attempt to enter Kevin's house, but he is shot in the face with Buzz's gun. As he goes downstairs to the basement, he slips down and says "ow" before trying to get up and enter. He is next seen finally entering and tries to turn on the lights. But the string is attached to a iron, which falls and hits his face, knocking him down. He then resorts to going upstairs. The tar sticks to his shoes and socks, causing them to come off, and Marv climbs up the tar-covered stairs. But near the top, he sees that he stepped on a nail. He screams while grabbing his foot, but he falls down onto his back on the bottom of the stairs. He climbs out and heads over to a window, but there are glass ornaments on the other side. Marv climbs in, and then yells in pain after stepping on them so hard he falls down. He shouts "I'M GONNA KILL THAT KID!" and gets up, but steps on more ornaments while doing so. He finally meets Harry (who's had his share of traps and looks like a chicken). They both join forces to capture Kevin and chase him to the stairs but they slip on some toy cars Kevin had laid out. They go upstairs, but a swinging can hits Marv in the face, knocking him down. Harry is hit by one as well, and lands on Marv. Marv remarks that Harry is "missing some teeth".
They get up and chase Keven upstairs; Harry trips over a wire and falls on his back. Marv jumps over the wire and Harry's unconscious body, and leaps at Kevin, landing on the floor holding onto Kevin's foot. But Kevin places Buzz's tarantula, Axl on Marv's face and flings it onto Harry's chest. Kevin runs upstairs while Marv grabs a steel cane and scares Harry and hits him hard. Harry grabs it back and hits him three times, calling him a jerk. They continue the chase and follow Kevin, only to see he is already on a treehouse on the other side of the backyard. Marv reluctantly climbs the rope leading there, but Kevin cuts the rope and they fall to the ground. They then look at each other knowing what they will do to Kevin. They chase him to the Murphys and capture him at the top of the flooded basement. As Harry is about to bite his fingers off, Marley, who had snuck in behind them, slams his shovel onto Marv's head, slamming it into the door and knocking him out. Harry turns around and only gets a glimpse of their attacker before being knocked out himself. Marv wakes up arrested by a police officer along with Harry and kicked in the rear by his boss after saying that they are the Wet Bandits. Harry and Marv are shoved into the police car and arrested, but not before Harry turns to glare at Kevin, hinting they will return one day for revenge.
Marv returns in the sequel when he and Harry end up breaking out of jail and catch a ride on a fish truck to New York City. He put double-sided sticky tape on one glove in order to steal 14 cents in donation money from a Santa Claus on the street. He makes up another nickname for him and Harry called the "Sticky Bandits". Marv is next seen walking behind The Model while crossing the street, and he turns around to see what Harry was looking at. The Model had stopped to see what time it was on her watch, and Marv bumped into her while also getting his hand stuck to her purse by accident. After managing to pull his hand away, Marv says he is sorry in French. The Model does not accept and slaps Marv across the face before leaving. Then Kevin, who was held hostage, touches the Model inappropriately in an attempt to escape. She punched Marv (assuming it was him), then she punched Harry (Kevin told her he did it).
Marv and Harry then see Kevin and try to catch him, Kevin uses beads from a necklace in order to trip them up. Marv is next seen in the toy store called Duncan's Toy Chest robbing the toy store with Harry, Kevin throws a rock with a letter to Mr. Duncan attached to it through the window. They then try to catch Kevin, following him to his Uncle Rob's house. Marv is then hit four times by bricks that Kevin throws down, leaving him very disoriented. He then goes up the stairs and tries to open the front door, but is tricked by the knob which is attached to a staple gun via a rope on the other side. When Marv finally pulls on the rope, the staple gun fires into the rump. When he turns, the gun fires into his groin, causing horrible pain. When he falls, the gun fires again into his nose. He then kicks the door open and unknowingly falls down a three-story drop to the basement. He then got up and slipped in a puddle of soap, fell on his back, and crashed into an entire shelf holding tins of paint, which fall on him. Going to the sink, he gets electric shocked. Recovering, he finds a rope placed conveniently like an exit out of the basement. However, the rope is attached to a bag of plaster which falls on him. Finally climbing out, he sees Harry on the ground with a cut-up ladder and they reunite. Going up the stairs, Kevin purposely tossed two paint cans down which miss. Laughing, they both go up the stairs only to be hit in the face with a metal pipe, then Kevin cut the ropes holding the pipe which falls on them. Later, they hear Kevin tormenting them and they pull on a doorknob which comes off and sends a tool box down the stairs, opening the door and crashing into them. When they climb down a rope to catch Kevin, Kevin sets it on fire and the burglars attempt to escape, only to fall several stories and get doused with varnish. They catch Kevin after he slips, and drag him to Central Park to kill him. However, the Pigeon Lady appears and throws a bucket full of birdseed on them, causing them to be mobbed by dozens of pigeons which deter the bandits long enough for the police to arrive and arrest them. The police find Kevin's photographs and his recorded audio footage. Marv then reveals that not only did they break into the toy store, they also escaped from prison, infuriating Harry, who strikes him multiple times to shut him up, but to no avail. As they are led away, Marv yells out to remember that they are not the Wet Bandits anymore, but the Sticky Bandits instead, to which Harry yells at Marv to shut up once more.
- Marv is played by Daniel Stern in this film. In the loose sequel Home Alone 4 which shares a shoddy continuity with the original two movies, he is portrayed by French Stewart. For more information on the Home Alone 4 version of Marv see Marvin Murchins (Home Alone 4).
- It is possible that Marv is Jewish, considering the fact he said "Happy Hanukkah Marv!" to himself while robbing the toy store in Home Alone 2. (Actor Daniel Stern is Jewish in real life.)
- On December 24, 2015, Daniel Stern posted a video on his Facebook and YouTube channel, reprising his role as an older Marv pleading for Harry to help him as Kevin is back and targeting all home invaders in a sadistic manner, recalling their injures when they fell for Kevin's booby traps. Marv then hears someone approaching and the video cuts to black as the sound clip of Marv screaming when Kevin put Axl the tarantula on his face from Home Alone is heard.
- The video itself is a response to the DRYVRS episode that featured Macaulay Culkin reprising his role as an older Kevin and torturing a home invader (which, in actuality, was a carjacker.) 
- Murchins height is 6'4.
- Murchins is possibly a foot taller than his accomplice, Harry Lyme.