"We're in a unique position to be able to intervene in this and to stop the war in Yemen and to do that as a friend", she told BBC Radio 4's Today programme.
The summit, attended by ministers from both countries, will focus on support for reforms in Saudi Arabia, trade relations, defence and security, according to Downing Street.
"She will also reiterate how seriously we take allegations of violations against global humanitarian law and emphasise the need to ensure that these are investigated swiftly and thoroughly", the spokesman added.
Her statements were interrupted briefly as opposition lawmakers cried "Shame!"
The prime minister intends to use the private dinner at Chequers, a 16th-century manor house 40 miles (60 km) northwest of London, to further press her concerns over the humanitarian crisis in Yemen, her spokesman said.
"Their involvement in Yemen came at the request of the legitimate government of the Yemen, it is backed by the UN Security Council and as such we support it".
Mohammed bin Salman, 32, is seen by some as a modernising force in the Gulf State.
The UK has faced its share of backlash from anti-war campaigners for selling arms to Saudi Arabia.
The criticism comes during a major row over bin Salman's three-day visit to the United Kingdom, which experts have called a state visit "in all but name".
However the visit comes amid protests over British arms sales to the Saudi government that have been used against civilians, including children, in the war in Yemen.
"Also, the visit to the Cathedral means that Saudi Arabia becomes more open to other cultures and religions".
Though the war will be a part of the discussion between the Saudi monarch and the British government, it may take a backseat in the face of the countries' financial interests.
Britain is vying to land the stock market listing of state oil firm Saudi Aramco, but no decision is expected this week.
Most detainees have now been released, and the authorities say they have arranged to seize more than $100 billion in assets.
Other demonstrators were planning to line outside Downing Street, where the crown prince will be welcomed by May for talks. According to the UN Human Rights Council, civilians have repeatedly been the victims of "unrelenting violations of worldwide humanitarian law". More similar programs are underway before the main planned rally on Wednesday.
Bin Salman's trip - during which he will also visit Cairo and NY - is the crown prince's first foreign tour as heir to the Saudi throne. (Photo by Reuters) "The UK should not welcome war criminal Mohammed bin Salman", the banners read.
The Labour leader said that 600,000 children in Yemen had cholera "because of the Saudi-led bombing campaign and the blockade", and asked why British arms sales to Saudi Arabia had "sharply increased".
"I urge Theresa May to now stand for values that Britain can be proud of, a nation that sets an example to the world, that is principled and compassionate and prioritises children's lives over trade deals".
And the crown prince's performance on the world stage will affect his standing at home and send signals about Saudi intentions in a region in turmoil. Theresa May is handing a major propaganda coup to the dictatorship.
"The regime has carried out atrocities against Saudi people for decades, and has inflicted a bad humanitarian catastrophe on the people of Yemen".
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