Known for her videos on her now-inactive YouTube channel Marzia (formerly CutiePieMarzia), Kjellberg has also ventured into writing, fashion design, and business.

[10] Kjellberg's YouTube channel was one of the most popular in the beauty and makeup genre; in May 2014, The Wall Street Journal reported that it attracted over 16 million viewers each month.

[16] Similarly, ABC had Kjellberg, among others, promote their new TV series, Selfie, via a YouTube marketing campaign.

[18] In the video she mentioned that at a point during her YouTube career, focusing on the website kept her in a bubble that negatively affected her mental health, although she resolved to reach out to others.

[20] Since March 2015, Kjellberg has launched several lines of fashion and design merchandise including nail polish shade, home decor products, and most notably clothing.

Kjellberg's "Amore" clothing line was positively received by Fink, who stated "the gold zipper and heart applique of this skirt are right on trend, yet the A-line silhouette is timeless.

[26] Both Mai and Tsuki Market, a unisex clothing and homeware brand that she owned with husband Felix Kjellberg,[27] are closed as of 2023.

[30] Aside from creating content on her own channel, Kjellberg has been a voice actress in various animated web series.

[31] Kjellberg also voiced the character Maya, based on her own dog, in a six-episode animated web series titled Pugatory.

[38] Their relationship has been highlighted by various media outlets,[39] with The Globe and Mail writing that her "calm personality balances out Felix's general wackiness.

[41][42] While living in Brighton, their house in Japan was burgled in late 2019; Kjellberg posted a statement online which included: "I know it is very materialistic, and should be happy with what I was left/have, but I can't hide the shock and sadness with all being taken away, just like that.