In an Easter message Charles said perpetrators needed to be brought to justice.
He labelled the recent killings “terrible deeds of darkness” and said he and the Duke of Sussex were filled with "immense sadness" after hearing stories of those affected by knife crime.
Writing in the Daily Telegraph on Good Friday, he spoke about the power of forgiveness, saying those striving to find solutions to the problem were "another example of light shining in the darkness".
He wrote: "'Recently, Prince Harry and I brought together some of those who have been affected by knife crime to see what more could be done to tackle this pervasive horror.
"Listening to those who have suffered from such attacks filled us both with immense sadness.
"But their remarkable determination to move forward and address the causes of such crime and to find solutions was, for me, yet another example of the light shining in the darkness."
The Government and police have come under intense pressure over violent crime.
Earlier this year a spate of fatal stabbings prompted warnings of a "national emergency".
There were 285 homicides where the method of killing was by a knife or sharp instrument in England and Wales in 2017/18 - the highest number since records started in 1946.
In the year to September, police recorded about 1.5 million "violence against the person" offences - a jump of nearly a fifth on the previous 12 months.
The prince said: "Of course, those who commit such brutal deeds need to face up to their crimes through being brought to justice.
"However, very often it is not the punishment that brings them to their senses and changes them, but rather the extraordinary power of the forgiveness from those they have hurt."
He also referred to the pair of attacks at mosques in Christchurch in New Zealand, where 50 people were killed by a gunman, writing: "Last month we saw another remarkable example of forgiveness following the utterly appalling attack on Muslims in Christchurch.
"The Easter message, with its emphasis on the timeless and universal values of forgiveness and reconciliation, gives hope to us all whether we live by faith or not.
"It encourages us to look for and to celebrate those moments in our own lives and in our own communities when we see the light overcoming the darkness."