The podcast began in 2015 and is one of the longest-running shows about writing and has been one of the few spaces where comedy writers can learn about their craft.
As their work has taken them into the worlds of book writing, comedy drama and live theatre, both presenters have been feeling for a while that it's getting harder to justify hosting a show with "Sitcom" in the title.
"The fact is that we're still enjoying it, and we wanted to get out before it starts to feel too much like we're covering the same ground," Cary said.
"I mean we're always covering the same ground," Dave added. "Very little changes in terms of what writers need to know, and it's always useful to repeat the important facts. But it'll be nice to go out feeling upbeat.
"But it's going to be a huge wrench."
Tom Gregory, who co-wrote Jack Carroll's Mobility sitcom which airs this Friday on BBC Three, said: "I can honestly say I've been a listener from the very beginning and have enjoyed every single episode - even going back and listening to some multiple times. It's true to say that without it, I'm not sure I'd be looking forward to having my first bit of comedy on the telly."
James is planning to do less sitcom teaching and more sitcom developing, writing and rewriting. Dave will continue to run courses and script reading, and publish books about TV, radio and online comedy writing.
"We decided to call it a day at Episode 222, because we're both big cricket fans," said James. "And seeing as probably almost none of you are cricket fans the significance of the number might well pass you by.
"Regulars may also miss the Sitcom Geeks drinking game, in which James urges listeners to down alcohol of choice every time Dave mentions Steptoe & Son or Frasier. Poor advice if you wish to stay sober."
"The show has been invaluable not just from a craft point of view but for the insight into the business," Tom added. "It'll leave a gaping hole in my listening schedule."