The man, who has not been named in order to protect the identity of the child, exchanged 3,000 Facebook messages with his son referring to her partner as 'k**b, and explaining to him how he could kill his mother.
Bradford Crown Court heard how the 'diabolical' plot was hatched in a series of messages between the man and his child. The father, described in court as 'bitter, spiteful and angry', got the boy to steal his mother's bank card and tell him her PIN. After stealing £300 from the account, he then instructed the child to hide the bank card under a rock.
In what were described as 'brainwashing' messages, he persuaded the lad to complain to people that his mother was 'selfish' and that he hated living with her and her partner.
Bradford Crown Court heard that between June and September last year, the man maliciously incited the boy to steal and claim that his mother had punched him in the face.
The court was told that the communications became even more sinister when the man began detailing how the child could poison his mum by applying nicotine (supplied by him) to her skin. He further suggested that her new partner's hair could then be put into the container of poison to implicate him. He told his son this would 'kill two birds with one stone'.
The man pleaded guilty to theft, fraud and perverting the course of justice, while a charge of encouraging or assisting in the commission of causing grievous bodily harm was dropped.
He was sentenced to 18 months in prison.
Despite hearing that the man had said 'I'd do the lot of them if I could', Judge Jonathan Rose said he was satisfied that he did not intend to kill or seriously injure the woman.
Prosecutor Kitty Taylor said the dad wanted his son to live with him after his mother entered into a new relationship. She said his actions were 'punishment to her from an embittered ex-partner'.
The judge said the man had directed his anger, malice and hatred on his son's mum, despite the fact she had never tried to stop him from seeing the child.
"I use the word reprehensible. It is unforgivable," Judge Rose said.
The man's own lawyer, Ian Hudson, admitted that his client's actions were 'disgraceful, despicable and diabolical' offences from a 'bitter, spiteful and angry' man.