She received the Primetime Emmy Award for Outstanding Supporting Actress in a Comedy Series for her role as Maryann Thorpe in the sitcom Cybill (1995–1998).

Baranski is also known for her film roles in Reversal of Fortune (1990), The Birdcage (1996), Cruel Intentions (1999), How the Grinch Stole Christmas (2000), Chicago (2002), Mamma Mia!

Baranski won two Tony Awards for Best Featured Actress in a Play for her role as Charlotte in Tom Stoppard's The Real Thing (1984) and as Chris Gorman in Neil Simon's Rumors (1989).

[6][7][8] She studied at New York City's Juilliard School[9] (Drama Division Group 3: 1970–1974),[10] where she graduated with a Bachelor of Fine Arts degree.

Other Broadway credits include Hurlyburly, The House of Blue Leaves, Rumors (for which she won her second Tony), Regrets Only, Nick & Nora, and the Encores!

At the Kennedy Center in Washington, D.C., Baranski starred as Mrs. Lovett in Sweeney Todd in 2002 (for which she won the 2003 Helen Hayes Award for Outstanding Actress in a Musical) and as the title character in Mame in 2006.

The original cast was Bradley Whitford (Bernard), Kathryn Hahn (Gloria), Christine Baranski (Berthe), Gina Gershon (Gabriella), and Mary McCormack (Gretchen).

Baranski also appeared in a one-night-only concert benefit performance of Stephen Sondheim's A Little Night Music for Roundabout Theatre Company as Countess Charlotte Malcolm on January 12, 2009.

Some of her better-known roles are as Katherine Archer in The Birdcage (1996), Martha May Whovier in How the Grinch Stole Christmas (2000), Mary Sunshine in Chicago (2002) and Connie Chasseur in The Ref (1994).

[16] Baranski has also appeared in the films 9½ Weeks (1986), Legal Eagles (1986), Reversal of Fortune (1990), Addams Family Values (1993), Jeffrey (1995), The Odd Couple II (1998) Bulworth (1998), Cruel Intentions (1999), Bowfinger (1999), Welcome to Mooseport (2004), Trolls (2016) and A Bad Moms Christmas (2017).

[17] A few years later, Baranski received an Emmy nomination for a guest starring role in the NBC series Frasier as a controversial tough love radio psychiatrist named Dr. Nora.

Due to the popularity of her first appearance, Baranski returned in the third season for the Christmas episode "The Maternal Congruence", receiving another Emmy nomination.

[20][21] From 2009 to 2016, Baranski played the role of Diane Lockhart, a top litigator and senior partner of a Chicago law firm on the CBS series The Good Wife.

Since 2022 she has portrayed Agnes van Rhijn in the Julian Fellowes-created HBO period drama The Gilded Age starring opposite Carrie Coon, Louisa Jacobson, and Cynthia Nixon.

As of 2021[update], Baranski was a practicing Catholic, at times accompanying her friend Robert King, the co-creator of The Good Fight, on the walk home following Sunday services.