Boyle, 25, is a centre half, who made over 150 appearances for the ‘Lilywhites’, helping them to three consecutive Irish titles, as well as into the group stages of the Europa League.
Horgan, 24, is a winger with 27 goals in 132 appearances for Dundalk in three seasons in the Irish Premier League, including their final goal in their European campaign last week in Tel Aviv.
Both players were called up by Martin O’Neill for the Republic of Ireland’s recent World Cup qualifier against Austria, along with new team-mate Aiden McGeady.
The duo have both agreed two-and-a-half year contracts which will begin from 1st January 2017, when the transfer windows open, but will require international clearance before they are eligible to play for their new club.
Speaking about his latest squad additions manager Simon Grayson said: “First and foremost we have signed two players who have attracted a lot of interest from a lot of clubs over the past few weeks and months and we have had to work hard to get them, which shows our intent as a football club.
“Both players have had great seasons in their league and in Europe, leading to their call ups for the Irish squad. They are young, hungry and looking to improve and will be excellent acquisitions for us.
“I spoke to Steve Guppy [Republic of Ireland coach] about both of them, who was very positive and we have watched them a number of times and they have been excellent at club level and handled the Europa League games very well.
“Daryl is a forward thinking players with a lot of goals. He makes things happen, has got a bit of pace about him, has a good delivery in him and he has scored a lot of goals this season.
“Andy is a good centre half, who can also handle the ball and both have shown their determination to join us by coming over a couple of times to meet us and got things done very quickly. They both have the desire to keep improving and joining a Championship club is the next progression for them – we have always tried to improve and we look forward to working with them.”
Boyle, who captained Dundalk during their Europa League fixtures said of his move: I can’t wait to get started. Once I heard Preston were interested in me and I got over and had a look around it was the only place I wanted to come to. I knew of the history of the club and I am now really looking forward to getting going.
“We have had a great run with Dundalk in Europe and won the league and then I got the international call up, so it has been a great year and this has capped it off.”
Whilst Horgan was also pleased to be making the move to Deepdale, adding: “I'm delighted to be here; I'm absolutely thrilled to get the deal over the line and now I'm really looking forward to getting into training and hopefully into the team.
“It's a massive club with a great history. It is a good team who like to try and play football, which was key for me. I met the manager and I was impressed by everything that he had to say, so that all helped massively, it just all seemed to fit and hopefully I can fit in here.”