The 24-year-old, who has signed until the end of the season, got his first experience of English football after joining Liverpool from Paris St Germain in 2008, going on to score 19 goals in 94 appearances for the Merseyside club.
He moved to Bolton in 2011 and scored 16 goals, including three in the SkyBet Championship this season.
Those figures may not be prolific, but the former France Under-21 cap was not surprised to be offered the chance to join Swansea's battle to remain in the Premier League.
He said: "It was not a surprise for me, it's a good opportunity for me to join a good club in the Premier League showing interest in me.
"I was really pleased to get the chance, I thought about it and decided to sign here.
"I was a part of Bolton, I was not talking to any other clubs but as a player you want to play in the Premier League and that is why I made the decision.
"It's for others to say if I am a Premier League player but my challenge is to help the team win as many games as I can. The objective is to stay up and to do that we have to win games."
Ngog is available for Tuesday's meeting with Fulham and, while manager Michael Laudrup may not throw him into immediate action, the Dane believes the forward brings something different to his squad.
"If we are talking position-wise we have been low in numbers recently and we are still in three competitions with the possibility of more injuries going on," he said.
"The other thing is to try and find abilities that you don't have. He's a different kind of forward, he has got that pace one-against-one that could be useful in games.
"What is very important when you look in the January window is that you look to find someone from this style of football.
"You can go outside and bring in foreigners with no experience of English football, but everyone needs time to adapt and we only have three-and-a-half months left in the league.
"So this is a player who has experience of this league from Liverpool and Bolton."