More than 2,500 gardai will be deployed across checkpoints and arterial routes across the country on Wednesday.
Much of the focus will be in Dublin amid fears that anti-lockdown activists will seek to use the public holiday to demonstrate against coronavirus restrictions.
There were ugly scenes close to Dublin’s St Stephen’s Green last month, when gardai were attacked with fireworks amid disturbances at a lockdown protest.
Gardai will be patrolling roads in the city through Wednesday and people will be asked for the reason for their journey to establish whether is it essential.
Several protest events are being planned via social media, by disparate groups in different locations in Dublin city centre.
Another protest is planned outside national broadcaster RTE in the south of the city.
The Garda will deploy personnel from the national units such as the dog unit, the mounted unit, air support and public order.
Checkpoints will be in place on arterial routes into the city and checks will be conducted on public transport over the course of St Patrick’s Day.
Gardai will stop people at bus stations and Luas stops to ensure they are not breaking Covid-19 regulations.
Ahead of the day, Deputy Garda Commissioner Anne Marie McMahon said: “As is the case with all protests, An Garda Siochana seeks to engage with protest groups in advance.
“However, some groups choose not to engage with us. It should also be noted that An Garda Siochana has no role in licensing or approving such protests.”