In a statement released on Saturday Mr Janetzki said he'd advised the party room of his decision after family challenges "during the last few years".
"Due to work demands across Queensland, these challenges were often met by my wife Mel alone," he said.
"Our three children also need more of me - and my heart knows that I need more of them.
"Every family makes choices and this decision is right for our family at this time."
He thanked Liberal leader David Crisafulli for his "friendship, compassion and understanding" towards his personal circumstances.
Mr Janetzki was elected deputy leader by his colleagues in November 2020.
He will take a "short break" before continuing in his role as shadow treasurer and shadow spokesman for investment and trade, he said.
Opposition leader David Crisafulli called his deputy a "fantastic parliamentarian" and an "even better family man".
"I respect and understand his decision to step down as deputy leader and the extensive travel that comes with it to focus on the health of his family," he said.
"I will miss him dearly as deputy leader. He has more to give in public life.
"The fact he is willing to continue to serve as shadow treasurer and shadow minister for investment and trade after taking a break with his family speaks volumes about the quality person he is."
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