Ramsey is one of the original voice actors for Rooster Teeth's sci-fi comedy machinima series Red vs. Blue (2003–present) as the voice of Dexter Grif.
 Since then, he has gone on to become an Internet celebrity, regularly appearing at conventions such as PAX and Com Blue with Red vs. Blue actors Burnie Burns, Gus Sorola and Joel Heyman on the Rooster Teeth Podcast.
He has only appeared on the podcast sporadically since September 2011, but was one of the hosts on a November 2014 episode of The Patch, Rooster Teeth's gaming podcast.
Ramsey's other work with Rooster Teeth includes voicing The Omnipotent Voice in the machinima series The Strangerhood (2004–2006), playing a fictionalized version of himself in both Captain Dynamic (2008) and Rooster Teeth Shorts (2009–present), being a "lab rat" in Immersion (2010), and voicing the Corpirate, the primary antagonist of the first season of the animated series X-Ray and Vav (2014).

In 2008, Ramsey started Achievement Hunter with his colleague Jack Pattillo, a department of Rooster Teeth Productions centered largely on video games.
The site originally focused on making videos of achievement guides and Easter eggs found in video games, but has since moved its primary focus to comedic "Let's Play" videos, wherein they play video games and provide humorous commentary, as well as other game-related videos and live-action content featuring the same personalities.

Additionally, he appeared in the bi-weekly reality series Happy Hour alongside his friend and coworker Gavin Free and his second wife Griffon Ramsey.

In June 2018, Rooster Teeth launched its first pop-up store in Los Angeles featuring a collection of shirts, hoodies, bags, and pins designed by Ramsey.

On September 23, 2019, it was announced that Ramsey had been appointed executive creative director of Rooster Teeth.
Ramsey is one of the original voice actors for Rooster Teeth's sci-fi comedy machinima series Red vs. Blue (2003–present) as the voice of Dexter Grif.  Since then, he has gone on to become an Internet celebrity, regularly appearing at conventions such as PAX and Com Blue with Red vs. Blue actors Burnie Burns, Gus Sorola and Joel Heyman on the Rooster Teeth Podcast. He has only appeared on the podcast sporadically since September 2011, but was one of the hosts on a November 2014 episode of The Patch, Rooster Teeth's gaming podcast. Ramsey's other work with Rooster Teeth includes voicing The Omnipotent Voice in the machinima series The Strangerhood (2004–2006), playing a fictionalized version of himself in both Captain Dynamic (2008) and Rooster Teeth Shorts (2009–present), being a "lab rat" in Immersion (2010), and voicing the Corpirate, the primary antagonist of the first season of the animated series X-Ray and Vav (2014).
In 2008, Ramsey started Achievement Hunter with his colleague Jack Pattillo, a department of Rooster Teeth Productions centered largely on video games. The site originally focused on making videos of achievement guides and Easter eggs found in video games, but has since moved its primary focus to comedic "Let's Play" videos, wherein they play video games and provide humorous commentary, as well as other game-related videos and live-action content featuring the same personalities.
Additionally, he appeared in the bi-weekly reality series Happy Hour alongside his friend and coworker Gavin Free and his second wife Griffon Ramsey.
In June 2018, Rooster Teeth launched its first pop-up store in Los Angeles featuring a collection of shirts, hoodies, bags, and pins designed by Ramsey.
On September 23, 2019, it was announced that Ramsey had been appointed executive creative director of Rooster Teeth.
Geoff Ramsey