In 2007, he began dating Heidi Montag, a primary cast member of the reality television series The Hills.

[2] In 2006, MTV developed the reality television series The Hills as the spin-off of Laguna Beach: The Real Orange County.

It originally chronicled the lives of Lauren Conrad, who appeared on its predecessor, her housemate Heidi Montag, and friends Audrina Patridge and Whitney Port.

[12] After leaving the series, Montag and Pratt became notorious for their antics and antagonistic roles, notably during an interview with Al Roker of Today,[13] and were described as "everything that's wrong with America".

[18] Pratt was arrested and jailed in Costa Rica on September 11, 2010, while attempting to board an aircraft with hunting weapons.

Other nominees for this award included Juan Pablo Galavis, Omarosa Manigault, Will Kirby, and Russell Hantz.

[20] In January 2013, Montag and Pratt (as a single entity) competed as housemates on Celebrity Big Brother 11,[21] where they notably developed a minor feud with singer and television personality Rylan Clark.

[23] On February 18, Channel 5 aired a one-off television special discussing Montag and Pratt's rise to prominence, titled Speidi: Scandal, Secrets & Surgery!.

However, they were evicted on day 25 against Kim Woodburn, Jessica Cunningham, Bianca Gascoigne and Jedward; after they finished in 9th place.

Pratt and Montag were reunited with their rival, Rylan Clark-Neal, on Big Brother's Bit on the Side that night.

Pratt developed a widespread fanbase on Snapchat by posting stories showing his family, daily life and his passion for hummingbirds.

His popularity led to him being nominated in January 2018 for Snapchatter of the Year at the 10th Annual Shorty Awards, eventually winning the category.

In December 2013, Pratt completed his undergraduate degree in political science at the University of Southern California after ten years.