The striker's arrival follows the loan signing of Harry Clarke from Ipswich Town on Monday.
Check out a selection of photos from Dykes' signing day below...
After putting pen to paper, the 30-year-old said: "I'm super pleased and I can't wait to get going. It's going to be really exciting for myself and my family, and I think there's going to be good times to come.
Speaking to the manager has been really exciting and really good. He's told me about the way that he sees me, the way he wants me to play and also how he wants his team to play, and it aligns with me."
The Scotsman was pleased to see a familiar face in Charlie Kelman when he arrived at Sparrows Lane.
"I played with Charlie a couple of times at QPR," he explained. "It was nice to see a familiar face when I came in and he was showing me around. I think he's got great potential and I think me and him can work well together going forward.
"I know a couple of players that are playing here at the moment and obviously coming to the stadium, it's a tough place to play and it excites me. Obviously the opportunity came up and I think I'm going to have a really good time here. I think we can do amazing things and, for myself, I want to show everyone what I'm capable of so hopefully I bring that straight here and make sure we win games."
Dykes brings a wealth of experience to Nathan Jones' ranks with over 150 Sky Bet Championship appearances to his name, as well as 48 international caps.
"Everyone sees the World Cup coming up and qualifying for Scotland was an amazing achievement for myself and the country, but my first thoughts are obviously finishing the season strong on a personal note with Charlton. That's my main focus and then, hopefully, if I do that, I can roll that into the World Cup and have a strong World Cup."
The Addicks return to The Valley on Saturday to take on Sheffield United. Click here to purchase your tickets now.
