It means today's game with Ireland takes on an added significance for Halfpenny as Wales look to make it two wins from two in this season's RBS 6 Nations.
"It is a huge honour for me and all my family and friends," said Halfpenny on his record-breaking achievement.
"To pull that Welsh jersey on for the first time was a special moment for me and to do it for the 50th time is just as exciting. Growing up as a rugby player, my dream was always to play for Wales, I wanted it so much. I just kept going and kept training hard.
"It's a huge privilege to be in the position I am, without the help of my team-mates, coaches, friends and family I wouldn't be in this position."
Halfpenny will lead Wales out at the Aviva Stadium in Dublin, a place which holds fond memories for the Cardiff Blues man. In 2012, it was his last-gasp penalty which guided Wales to a narrow victory and gave them the impetus for a third Grand Slam in eight years.
"It was a real special moment and capped a very proud day for me," said Halfpenny, as he looked back on his last visit to Dublin.
"I can remember it like it was yesterday, just because it was the next opportunity I got to win a game for Wales after the semi-final of the World Cup.
"I remember thinking if I had another chance to win a game for Wales, I wanted to take it. I have had some big kicks since - that was one I was especially nervous about, my heart was racing. But the moment I hit it, I knew it was over."
Both Wales and Ireland go into today's game on the back of wins on the opening weekend. There has been plenty of recent rivalry between the two sides, as well as both fielding a number of players who featured on last summer's successful British & Irish Lions tour.
Recent statistics show the encounter could be hard to call. Ireland have not begun an RBS 6 Nations campaign with a pair of victories since they won the Grand Slam in 2009, while Wales' only defeat in their last 11 Championship came against Ireland in last year's tournament opener. Wales have also won on two of their last three visits to Dublin, at Croke Park in 2008 and at the Aviva Stadium two years ago.
Halfpenny admits Gatland's side need to improve from their 23-15 victory over Italy but says Wales are more than up for the challenge.
"We conceded two tries from turnovers and mistakes - the second one I was involved with," added the Gorseinon product.
"I have to put my hand up for that because I have to see the defence and know they are reacting. The moment it left my hands, I could tell what was going to happen but at that point, I could not stop it.
"You never stop learning in rugby and I learned a huge lesson from that. It was the first international interception of my career and hopefully it won't happen again. We know how big this game is for us and it's one we are excited about."
Asked for his view on Halfpenny, head coach Gatland said: "He's been absolutely outstanding. He is the ultimate professional and has a huge amount of respect from the players.
"The thing with Sam as captain is he does not get too many chances to walk out in front because of these milestones for all the other players!
"But it's a great honour for Leigh to achieve and hopefully we can put in a winning performance for his 50th cap."