Frankel is best known as an original cast member of the Bravo reality television series The Real Housewives of New York City, starring in 8 of the 14 seasons since its 2008 premiere.

Outside of her work in television, Frankel is the founder of Skinnygirl, a lifestyle brand, and BStrong, a philanthropic organization that has provided disaster relief.

While she landed some small acting roles, she worked as an assistant to Kathy Hilton, sometimes taking her daughters Paris and Nikki out for ice cream or picking them up from school.

[15] In 2003, Frankel started BethennyBakes, a baking business that made egg-free, wheat-free and dairy-free cookies and meal delivery in New York City.

[15][18] In 2008, Frankel began starring in the reality television series The Real Housewives of New York City, which premiered in March on Bravo.

[28] Frankel starred in the HBO Max reality competition series titled The Big Shot with Bethenny, which she also produced alongside Burnett.

[32] In one of her earliest activities in philanthropy, Frankel posed nude for a PETA billboard in September 2009 for its "I'd rather go naked than wear fur" campaign, which used celebrities and other personalities.

In spring 2010, she released an exercise DVD, Body by Bethenny, and an audiobook, The Skinnygirl Rules, which summarized her two prior books.

The cocktail line was sold to Beam Global for a reported $120 million in 2011,[37] but Frankel kept the Skinnygirl brand name to sell a variety of foods including dips, shakes, candy, deli meat, sweeteners, jellies, popcorn, and salad dressings.

[39] Frankel is the founder of BStrong, a philanthropic arm originally formed to assist women, which has increasingly participated in disaster relief around the world.

[40] In 2017, the organization raised $300,000 in donations and supplies for the victims of Hurricane Harvey,[41] after which Frankel visited Houston, Texas to distribute these items.

[41][43] Also in the same year, Frankel chartered four planes to Puerto Rico and distributed medical supplies, food, water, and hygiene products in assisting with Hurricane Maria relief efforts.

[47] She stated that reality television personalities are subject to exploitation and intense scrutiny and deserve increased protection and worker's rights.

[48] Frankel's proposals for a union would call for reality television personalities to earn residual-like payments, a minimum wage of $5,000 per episodic appearance with a raise for each season, retrospective compensation, and the freedom to quit filming at any time without risking financial penalty.

[47][49] Frankel has enlisted attorneys Bryan Freedman and Mark Geragos to investigate the problematic treatment of reality television personalities.

[58] She met film producer and commercial real estate developer Paul Bernon[59] on a dating app in 2018 and they were engaged in 2021, but Frankel said she ended the relationship after nearly six years because she was not happy.