Since joining the club’s academy, Botham has made 78 first team appearances and believes “there is plenty more to come”.
“There is a huge amount of talent, plenty of competition and a real hunger to keep driving forward,” he said.
“On a personal level, I am just happy to have had an injury free run and been able to show what I am capable of both for Cardiff and at international level.”
Cardiff coach Corniel van Zyl said: “It’s great to keep Jim at Cardiff.
“He has an exceptional athletic ability and always embraces the physical challenge. He has a massive engine, a very good skillset and is very handy right across the pitch.”
“He is really deep rooted in the club and contributes a lot off the pitch. He is someone who always looks out for his mates and people at the club.
“So I’m excited for his future here and he will be a really important figure for us.”