Educated in theatre arts at Brown University, Krasinski has film credits including Leatherheads (2008), Away We Go (2009), It's Complicated (2009), Something Borrowed (2011), Promised Land (2012), and 13 Hours: The Secret Soldiers of Benghazi (2016).

[14][15] At Brown, he was a member of the sketch comedy group Out of Bounds[16] and helped coach youth basketball at the Gordon School in East Providence, Rhode Island.

[25] In 2006, Krasinski co-starred in Jason Carvey's independently produced, direct-to-DVD heist comedy A New Wave with Andrew Keegan and Lacey Chabert.

In 2007, he co-starred with Anna Faris and Danny Masterson as Brevin in Gregg Araki's independent stoner comedy Smiley Face (2007).

[27] Krasinski guest-starred in a number of television series including Law & Order: Criminal Intent, Without a Trace, Ed,[28] American Dad!

In 2008, Krasinski appeared with Renée Zellweger and George Clooney in the latter's directorial venture Leatherheads (2008), a period comedy about the early years of professional American football.

He wrote the screenplay for the film based on David Foster Wallace's collection of short stories, played a minor role in it and also served as producer.

Scott wrote that "though this experiment doesn't quite succeed, there's enough intelligence and insight in this movie to make it worth the attempt" while Elizabeth Weitzman from New York Daily News felt that "Krasinski deserves credit for having the ambition to adapt material as difficult as David Foster Wallace's short stories.

In his review, Michael Rechtshaffen from The Hollywood Reporter, said "terrific performances make this tender if slight little film worth the trip".

[34] His third 2009 role was in Nancy Meyers' romantic comedy It's Complicated as part of an ensemble cast that included Meryl Streep, Steve Martin, Lake Bell and Alec Baldwin.

In 2011, Krasinski co-starred with Ginnifer Goodwin, Kate Hudson and Colin Egglesfield in the romantic comedy Something Borrowed, based on Emily Giffin's novel of the same name.

[38] Krasinski starred opposite Drew Barrymore in the biopic film Big Miracle (2012), which covers Operation Breakthrough, the 1988 international effort to rescue gray whales from being trapped in ice near Point Barrow, Alaska.

[43] Next, Krasinski starred in, co-produced and co-wrote the screenplay for the drama Promised Land with Matt Damon based on a story by Dave Eggers that released on December 28, 2012.

[48] Under the banner, Krasinski and Seeger along with Stephen Merchant, became executive producers of the live-action/animated sitcom Dream Corp, LLC created by Daniel Stessen on Adult Swim.

[49] Krasinski along with Merchant are also executive producers of the musical reality competition television series Lip Sync Battle which debuted on the American cable network Spike, on Thursday April 2, 2015.

[53] In 2014, Krasinski collaborated with his Promised Land co-star and co-writer Matt Damon on the critically acclaimed 2016 drama Manchester by the Sea which starred Casey Affleck and Michelle Williams.

The film follows six members of Annex Security Team who fought to defend the American diplomatic compound in Benghazi, Libya after waves of attacks by Islamic militants on September 11, 2012.

[59] Krasinski also starred in the film alongside an ensemble cast of Sharlto Copley, Charlie Day, Richard Jenkins, Anna Kendrick and Margo Martindale.

Peter Travers of Rolling Stone wrote that Krasinski "tackles the most clichéd genre in the movie business – the dysfunctional family dramedy" and that "he pulls it off with uncommon humor and compassion.

"[60] Krasinski starred in the world premiere of the Off-Broadway play Dry Powder with Hank Azaria, Claire Danes, and Sanjit De Silva which was directed by Thomas Kail.

[63] In October 2016, he directed a live reading of the Good Will Hunting (1997) screenplay at New York's Skirball Theater in a one-off stage appearance of both the original stars Ben Affleck and Matt Damon along with Emily Blunt.

[66] In 2018, Krasinski directed and co-wrote the film A Quiet Place, a post-apocalyptic horror thriller, in which he also co-starred with his wife Emily Blunt.

The series focused on highlighting good news at the time, while featuring celebrities including Steve Carell, Robert De Niro, the entire original Broadway cast of Hamilton, Brad Pitt, Samuel L. Jackson, Oprah Winfrey, Emma Stone, Ryan Reynolds, Steven Spielberg, Jon Stewart, Malala Yousafzai and the cast of The Office.

[83][84] On Rotten Tomatoes, the sequel earned a 91% rating based on 355 reviews, with the website's consensus stating that the "nerve-wracking" film expanded "the terrifying world of the franchise without losing track of its heart".

[96] He has also narrated commercials for Apple TV, Verizon Wireless, Esurance,[97] BlackBerry Storm,[98] My Coke Rewards,[99] and Carnival Cruise Lines,[100] and has appeared in print advertisements for Gap.

[110] In May 2020, Krasinski partnered with Sevenly, 5th Element, and the Starbucks Foundation to launch Some Good Merch, an online merchandise store designed to raise financial support for multiple social causes during the COVID-19 pandemic.

[118] At this time, donations to Trauma Free World also went towards the international "Signs for Hope" program, which assists in the training of trauma-informed care for deaf children and orphans.

[121][122] Partnering with the Omaze foundation in 2018, Krasinski and his wife also raised money for the Malala Fund, which advocates for education rights for girls and women.

[124] From March to December 2020, Krasinski and his Sunday Night Productions team created multiple fundraising and donation opportunities through their Some Good News web show.

This included providing three months of free cellphone service for all nurses and doctors in the United States through AT&T and lifetime season pass tickets for Boston-based front-line medical workers to Boston Red Sox baseball games.