New measures include a statutory defence for victims, which strengthens their protection against inappropriate prosecutions for crimes committed as part of their exploitation.
The law will also encourage courts to use seized assets from perpetrators to compensate victims, and provide better access to civil legal aid for slavery victims.
Official figures estimate that 10,000 to 13,000 people remain trapped in modern day slavery in the UK.
Forms of modern slavery across the UK include forced criminality, such as cultivating drugs, forced labour in agriculture, construction sites or nail bars, sexual exploitation and domestic servitude.
The Salvation Army, which holds the Home Office contract for managing safe houses for adult trafficking victims, has helped more than 2,500 men, women and families over the past four years.
Responding to the new legal measures, Anne Read, anti-trafficking and slavery director at the Salvation Army, said: "Everyone engaged in this work is pleased that something is being done, there is now an escalation in effort.
"There are thousands of people trapped in situations not of their choosing, doing things they do not what to do and things need to be done to help them and to stop anybody else being sold in to slavery."
Graham Symonds is the Operations Manager at Hope for Justice, a Christian charity campaigning against human trafficking.
He told Premier's News Hour: "Before now trafficking has been known as a high profit, low risk crime, with a maximum sentence of 14 years.
"Today this changes completely. We think it much better reflects justice for the victims, some of whom suffer the most appalling crimes imaginable."
The new law followed an intense campaign by Premier to increase protection for people who were victims of modern day slavery and human trafficking.
Graham Symonds speaking to Premier's Hannah Tooley: