Los Angeles bank employee Carl Allen (Jim Carrey) has become withdrawn and depressed since his divorce from his wife Stephanie (Molly Sims). Routinely ignoring his friends, he has grown used to spending his spare time watching DVDs alone in his apartment and his outlook on life has become inherently negative. But when an old friend (John Michael Higgins) persuades him to attend the "Yes!" self-improvement seminar, stern motivational guru Terrence Bundley (Terence Stamp) publicly browbeats him into making a covenant with himself. Carl reluctantly promises to stop being a "No Man" and vows to answer "Yes!" to every opportunity, request or invitation that presents itself thereafter.

After the seminar, saying "yes" to a homeless man's requests only leaves Carl stranded in Elysian Park with his phone battery dead, no money, and his gas tank empty. Disillusioned, he hikes to a gas station, cursing himself for being so credulous and gullible. But at the gas station he meets Allison (Zooey Deschanel), an eccentric young woman who is refueling her scooter. She gives him a hair-raising ride back to his car, and spontaneously kisses him before she rides off.

After this experience, Carl adopts a positive mentality and seizes every opportunity that comes his way. He takes flying lessons, receives oral sex from his elderly neighbor (albeit reluctantly) after an incident that occurs when he says no to it, attends Korean language classes, learns to play the guitar, and even joins a Persian dating website after he receives a pop-up on one of his computers. Saying "yes" constantly works to Carl's advantage. After accepting concert tickets from a promoter whom he has previously ignored, he sees an idiosyncratic band whose lead singer turns out to be Allison. He is charmed by her quirkiness; she is charmed by his spontaneity; and the two begin dating. He earns a promotion at work after his many approved loans open new territory for the bank in the area of microcredit. Making use of his guitar lessons, he wins public acclaim by playing Third Eye Blind's song "Jumper" to persuade a man (Luis Guzman) not to commit suicide by jumping off a ledge.

As their relationship blossoms, Carl and Allison meet at the airport for a spontaneous weekend excursion. Having decided to take the first plane out of town, no matter where its destination, they end up in Lincoln, Nebraska, where they explore the Frank H. Woods Telephone Museum, attend a college football game, and go skeet shooting. As they shelter from the rain in an isolated barn, Allison asks Carl to move in with her and he hesitantly agrees. But while checking in for the return flight, Carl is detained by FBI agents, who have profiled him as a potential terrorist because he has taken flying lessons, studied Korean, approved a loan to a fertilizer company, met an Iranian mail-order bride, and bought plane tickets at the last minute to a destination that they believe to be an unlikely holiday destination.

Carl's lawyer and best friend Pete travels to Nebraska to explain Carl's odd habits, lessons, and decisions. As Allison finds out about Carl's motivational covenant, she begins to doubt whether his commitment to her was ever sincere. Deciding that she can no longer trust a man who is obliged always to respond in the affirmative, regardless of his true feelings, she leaves Carl at the airport after the officer unlocks her handcuffs.

Soon afterward, Carl receives a tearful phone call from his ex-wife whose new partner has walked out on her. When Carl goes to Stephanie's apartment to comfort her, she kisses him passionately and asks whether they can get back together. After Carl emphatically says "no," his luck again takes a turn for the worse. The elevator in which he tries to leave Stephanie's building almost snaps free of its cable, a black cat crosses his path, and his car gets clamped and towed.

In desperation, Carl goes to the convention center where the "Yes!" seminar is held, and hides in the backseat of Bundley's convertible so that he can beg to be released from the covenant. Carl emerges as Bundley drives off, startling him to run a red light and collide with an oncoming vehicle. The two are taken to hospital. After Carl recovers consciousness, Bundley informs Carl that there was no "covenant." The point was merely to open Carl's mind to other possibilities, but not to take away his ability to say "no" if he needed to.

Freed from this restraint, Carl leaves the hospital on a Ducati Hypermotard motorcycle, wearing only a hospital gown. He finds Allison and admits that he does not want to move in with her just yet, but tells her that she inspired him, and genuinely loves and wants her — and has not been with her just because he has been compelled to say "yes". The couple share a few kisses, occasionally interrupted by another photographer snapping pics.

At the end of the movie, Carl and Allison are seen donating a truckload of clothes to a local homeless shelter. Cutting to the scene of the "Yes!" seminar, Bundley is seen walking onstage to several hundred naked audience members. It is implied that the participants have said "Yes!" to donating their clothes to charity.
After some credits, a scene shows Carl and Allison on a long stretch of winding highway. Carl has agreed to test the product of one of the people whom he gave a loan. Both are wearing a full body suit with wheels on the elbows, calves, heels, feet, back, and various other strategically placed body parts, which is what the man invented for better extreme sports. They both "skate" all the way down the highway.

Yes Man SoundTrack

• Ringtone / opening song – Separate Ways (Worlds Apart) by Journey
• Bigfoot Lodge – Old Enough by The Raconteurs
• To Lick Your Boots by Eels
• Bus Stop Boxer by Eels
• Scene from the movie Saw – Fuck This Shit by Charlie Clouser
• Eyes Down by Eels
• The Sound Of Fear by Eels
• Your Lucky Day In Hell by Eels
• The Spaces Between by Expatriate
• Persian wife web site – El B’Nia by Maghrebika
• Bar song – Swollen Summer by The Bravery
• Dancing game – Flowers by Terra
• Staring At The Rude Bois by Gallows
• Emperor Waltz by Lawrence Welk
• First song by Zoeey Deschanel – Journey To The Center Of The Earth by Von Iva and Zooey Deschanel
• Bar song – Hyper Enough by Superchunk
• Playing keyboard – Star Spangled Banner by Zooey Deschanel
• Zooey Deschanel sings – Uh by Huh by Munchausen by Proxy (f/ Zooey Deschanel & Von Iva)
• In A Jar by Dinosaur Jr
• Last Zoeey Deschanel song – Sweet Ballad by Munchausen by Proxy (f/ Zooey Deschanel & Von Iva)
• 6 am running – Helicopter by Bloc Party
• Talking at Griffith Observatory – Blinking Lights (For You) by Eels
• Theme From Blinking Lights by Eels
• First Harry Potter song – A Reunion Of Friends by John Williams
• Second Harry Potter song – Leaving Hogwarts by John Williams
• Wooden Nickels by Eels
• Ana Ng by They Might Be Giants
• Animal by Eels
• Water Music by Aradia Ensemble
• Hollywood Bowl – Can’t Buy Me Love by Jim Carrey and Zooey Deschanel (originally performed by The Beatles)
• Talks the man off the ledge – Jumper by Jim Carrey (originally performed by Third Eye Blind)
• Nebraska football game – Mr. Touchdown, U.S.A. by The University of Nebraska-Lincoln Cornhusker Marching Band
• Yes To You by Alice Faye
• Umbrellas To Mend by Frisco Jass Band
• Lazer Gun by Dr. Dud
• Song at the bar during wedding shower – Stomp! by The Brothers Johnson
• The breakup – The Good Old Days by Eels
• Let’s Get Small by Trouble Funk
• Cool Jerk by The Go by Go’s
• Bridal shower – Carry On by Jean Knight
• Second bridal shower song – Olde Mill Inn by Blackmore’s Night
• A Little Bit Of Basie by Red Garland
• Flyswatter by Eels
• Keystar by Munchausen by Proxy (f/ Zooey Deschanel & Von Iva)
• Prologue by John Williams
• Somebody Loves You by Eels
• Riding on the Ducati – Separate Ways (Worlds Apart) by Journey
• Yes Man by Munchausen by Proxy (f/ Zooey Deschanel & Von Iva)
• Man Up by Eels
• Original music for Yes Man by Lyle Workman and Mark Oliver Everett

Yes Man Trailer