The government decided earlier this week to press ahead with the elections, which the main opposition party is planning to boycott, despite warnings that it could lead to more violence without resolving an increasingly bitter political divide.
Ms Yingluck said yesterday: "Even though protests are going on, I believe you can go out and vote. I ask everyone involved in the election, particularly security forces, to ensure people can out and vote."
Labour Minister Chalerm Yoobamrung, who is in charge of a state of emergency imposed last week, said 10,000 police would be mobilised in the capital on polling day. He added: "Those who are thinking of going and shutting polling stations should think twice because the police will not allow them to."
Protesters prevented early voting at many polling stations in Bangkok last Sunday and they have vowed to do so again.
The protesters took to the streets in November in the latest eruption of a political conflict that has gripped Thailand for eight years.
They accuse Ms Yingluck of being a puppet of her brother, ousted former premier Thaksin Shinawatra, who lives in self-imposed exile but is still said to have huge influence.