Mrs Zito says she was "speechless" when she learnt about her OBE award.
The 37-year-old was widowed in 1992 when her husband of three months, Jonathan, was stabbed in the eye by a schizophrenic.
Christopher Clunis, now 39, had been released from hospital under the care in the community programme.
Two years later Mrs Zito set up the Zito Trust to campaign for more control over severely mentally ill patients who are released into the community.
Celebrating her honour, Mrs Zito said of the award: "I have tried so hard for such a long time and to be recognised like this, nationally and publicly, is amazing.
"It shows how hard we have all worked over the last few years. It's just a relief to be recognised.
"You feel sometimes that people don't listen or people get tired of your voice and it's so good to see that something good has come out of a terrible loss for so many people."
Mrs Zito, from south London, who has since had two sons with a new partner, said the award was tinged with sadness because it was related to her husband's death.
But she said: "This is a cause for celebration at what is really a very difficult time.
"The award is recognition of my status as a victim and therefore recognises other individuals who have been through similar circumstances."
Clunis was detained indefinitely in Rampton special hospital after pleading guilty to the manslaughter of Mr Zito.