Downs first gained attention for his role in the Comedy Central series Broad City, which ran for five seasons and for which he was also a writer, director and executive producer.

He attended the Peck School for seventh and eighth grade where he performed in the Twelfth Night and won a drama award.

[7] Downs has been creating digital shorts with Lucia Aniello under the moniker Paulilu since the pair met at the Upright Citizens Brigade.

Retitled Rough Night and released in 2017, Aniello directed, while Downs co-starred opposite Scarlett Johansson in the film.

[10] On April 20, 2016 Downs starred in the Comedy Central miniseries Time Traveling Bong alongside Broad City co-star Ilana Glazer.

[11] In 2018, Downs co-starred in Netflix's summer comedy Like Father opposite Kristen Bell, Kelsey Grammer, and Seth Rogen.