Dan Evans had pleaded guilty in September to two counts of phone hacking as well as making illegal payments to officials and perverting the course of justice.
He was a prosecution witness against his former editor Andy Coulson in the hacking trial.
A judge at the Old Bailey court reduced Evans' sentence to 10 months, which is suspended for a period of one year and if he does not break court conditions he may not have to serve any time in prison.
He said he had taken the guilty pleas and Evans' agreement to give evidence in the hacking trial and possibly other future trials into account.
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"In the circumstances of this case, and in particular the cooperation that Mr Evans has given and has agreed to give the police and the prosecution in the future as compared with the lack of cooperation from others, I do feel able to suspend the sentence for a period of 12 months," the judge said.
"I would not have done that had Mr Evans not made a clean breast of his involvement in these offences," he added.
He also admitted hacking phones while he worked for the 'Sunday Mirror'.
Earlier this month, former 'News of the World' editor Coulson was jailed for 18 months for conspiracy to hack phones.
Five fellow defendants - including former News International chief Rebekah Brooks - were cleared of all charges.
Justice Saunders said Evans was one of "the only people who have been prepared to give evidence of their knowledge and involvement in phone hacking at the News of the World".