Shortly before the final episode of the ABC1 legal drama Crownies was broadcast in November 2011, David Knox from TV Tonight reported that the series could continue in the form of a spin-off.

[3][4] Janet King was produced by Karl Zwicky, Jane Allen and Lisa Scott, with Hilary Bonney acting as story consultant.

Carole Sklan, ABC's Head of Fiction, commented "Screentime has developed an exciting drama series about the fabulous character, Janet King.

The series looks at the dilemmas of a contemporary woman who returns to work after a year's maternity leave and is flung into a shocking prosecution that involves layers of intrigue played out at the highest levels of power.

Her former colleague Richard Stirling (Hamish Michael) is now a barrister for some of the athletes involved, while Owen Mitchell (Damian Walshe-Howling) has become the head of the DPP.

[7] Anthony Soegito from If Magazine revealed that Marta Dusseldorp would return as Janet King, while many of the characters that became established on Crownies would also make appearances.

[4] These included; Hamish Michael (Richard Stirling), Ella Scott Lynch (Erin O'Shaughnessy), Andrea Demetriades (Lina Badir), Peter Kowitz (Tony Gillies), Christopher Morris (Andy Campbell), Indiana Evans (Tatum Novak), Jeanette Cronin (Tracey Samuels), Aimee Pedersen (Ashleigh Larsson) and Lewis Fitz-Gerald (David Sinclair).

[8] John Howard, Sonia Todd, Jessica Napier, Deborah Kennedy and Tiriel Mora also have roles in the series.

[8] Todd Lasance and Daniel Lissing did not reprise their respective roles as Ben McMahon and Conrad De Groot.

[9] Joining Dusseldorp as title character Janet King for series 2 include former Crownies originals; Hamish Michael (Richard Stirling), Andrea Demetriades (Lina Badir), Christopher Morris (Andy Campbell) and Peter Kowitz (Tony Gillies), as well as, Janet King season one cast members, Damian Walshe-Howling (Owen Mitchell) and Terry Serio (Terry Renner).

New faces include Leah Purcell, Philip Quast, Anita Hegh, Aaron Jeffery, Genevieve Hegney, Nicholas Hope and Ewen Leslie.

Joining them was Don Hany, Robert Mammone, Susie Porter, Andrew Ryan, Huw Higginson, Steve Le Marquand, Arka Das, Adam Demos,[11] Geraldine Viswanathan and Zoe Terakes.