By Agence France-Presse
The team led by Patrick Cammaert, a retired Dutch general, made their first stop in Aden where the internationally-recognised government is based.
While in the city Cammaert is due to meet with leaders, according to a Yemeni official, before travelling to the rebel-held capital Sanaa and onwards to Hodeida.
The team's arrival comes a day after the UN Security Council unanimously approved a resolution authorising the deployment of observers to Hodeida, a lifeline port city which serves as the entry point for the majority of imports to war-torn Yemen.
The UN team is due to secure the functioning of the port as well as supervise the withdrawal of fighters from the city.
The resolution submitted by Britain also endorses the outcome of UN-brokered peace negotiations in Sweden last week, where the warring parties agreed to the Hodeida truce which came into force on Tuesday.
The text approved by the Security Council "insists on the full respect by all parties of the ceasefire agreed" for Hodeida.
It authorises the United Nations to "establish and deploy, for an initial period of 30 days from the adoption of this resolution, an advance team to begin monitoring" the ceasefire, under Cammaert's leadership.