It won’t be too long a wait for The Diplomat Season 4. Netflix shared an update on the Emmy-nominated drama’s upcoming season on January 7 as part of its 2026 programming slate, confirming that the new season will come out this year.
The Diplomat stars Keri Russell and Rufus Sewell as a married couple with immense political power, Kate and Hal Wyler. Kate is the U.K. Ambassador, but she added Second Lady to her resume in Season 3 after Hal, also a former ambassador, unexpectedly became vice president of the United States, a job he was trying to snag for Kate in every season prior. Kate and Hal navigate how their relationship has a real-world impact, and how the high-stakes pressures of their careers both make and break their marriage, throughout the series.
As previously announced, Nana Mensah will be a series regular in The Diplomat Season 4. The actor has played Billie Appiah, the White House chief of staff, since Season 1. Mensah joins Allison Janney (Grace Penn) and Bradley Whitford (Todd Penn), who have also been upped to series regulars in the fourth season, which is set to start filming this fall. The Diplomat Season 3 came out in full on October 16 on Netflix.
Mensah’s Billie started as chief of staff to President William Rayburn (Michael McKean). She was fiercely loyal to Rayburn and was one of the people trying to oust his vice president, Grace Penn (Janney), from her office earlier in the series. The plan was to replace Penn with Kate, but fate had other plans. Billie found herself serving as Penn’s chief of staff after the sudden death of Rayburn, who died while on the phone with Hal, as he delivered the distressing news about Penn’s involvement in the strike on the British ship in the Persian Gulf.
West Wing alums Janney and Whitford have been guest stars in the Emmy-nominated political drama until now. Janney first debuted in Season 2 as Vice President Grace Penn. Grace became president in the Season 2 finale, and Season 3 showed the aftermath. Whitford made his debut in the third season as Todd Penn, Grace’s husband, who is now the first gentleman.
Here’s everything we know about The Diplomat Season 4. (And here, you can take a deep dive into The Diplomat Season 3 finale in our interviews with cast and creators.)
When does The Diplomat Season 4 premiere?
Netflix
The Diplomat Season 4 comes out in 2026 on Netflix. An exact premiere date will be announced at a later time. Filming started in Fall 2025, after Season 3 came out in October.
What happened in The Diplomat Season 3?
In Season 3 of The Diplomat, Ambassador Kate Wyler lives the particular nightmare that is getting what you want. She just accused Vice President Grace Penn of hatching a terrorist plot and admitted she’s after the VP’s job. But now the president is dead, Kate’s husband Hal may have inadvertently killed him, and Grace Penn is the leader of the free world. None of this slows Hal’s campaign to land Kate the vice presidency. Kate steps into a role she never wanted, with a freedom she never expected, an increasingly complicated friendship with Foreign Secretary Austin Dennison (David Gyasi), and an unnerving bond with first gentleman Todd Penn (Whitford).
“Everything we learned about Grace Penn at the end of Season 2 makes the relationship between the U.S. and the U.K. a lot more complicated going forward now that she’s president,” creator/executive producer Deborah Cahn told TV Insider. “Getting rid of her is not really viable in the same way…or maybe it is.”
Who is in The Diplomat cast?
In addition to Russell, Sewell, Janney, Whitford, Mensah, and Gyasi, The Diplomat stars Ali Ahn, Rory Kinnear, and Ato Essandoh. Rivals star Aidan Turner is also in Season 3 in a recurring role.
The series is created by showrunner/executive producer Cahn and is executive produced by Russell, Janice Williams, and Alex Graves.
The Diplomat, Season 4 Premiere, 2026, Netflix
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