By the end of it, the former One Direction singer was hailed as a legend, after firstly entering the stage and asking the crowd "Conas atá tú?", which is Irish for "How are you?", in case you didn't know.
Half way through his set, Styles stopped the show to check on a fan who had appeared to have lost their footing.
"Give her a bit of space and water. Is everybody else good?", Styles told the audience. He also asked the supporter in question, "You good? Did you fall, is it slippy?", before jokingly referring to getting "headbutted" a few years back.
He was not joking though as back in 2010 while performing with One Direction, Harry Styles and Niall Horan were headbutted by a supporter at a show in Tallaght.
"Thanks for all the support over the years apart from the time I got headbutted because I went to Tallaght", Styles said while on stage. "Is anyone in here tonight from Tallaght? I forgive you Tallaght, I forgive you".
It is fair to say Harry Styles brought the house down at Slane last night. Along with delving into his own back catalogue with hits such as "Watermelon Sugar' and 'Adore You' among others, Styles also treated the fans to some 1D specials, including "What Makes You Beautiful', and 'Stockholm Syndrome'.
Reacting to his performance on social media, one fan among many, hailed Styles as a "legend".
"Harry Styles is a legend. Tonight at Slane he spotted a girl who took a slip and fall, went over to check on her and asked for someone to get her water. Fair play to him", they wrote.
