"It's a delight for me," Ngog told the Swansea website. "I think Swansea are a very good club. They have shown over the last couple of years that they are a good Premier League side.
"Swansea are a team who like to keep the ball and play good football. The manager (Michael Laudrup) was obviously a top player and as a manager he has proven he is very good as well. It will be really interesting to work with him."
Swansea have slipped to 15th in the Premier League table and have been short of attacking options since losing last season's leading scorer Michu to injury last month.
Ngog could make his debut in the home league game against fellow strugglers Fulham on Tuesday.
The 24-year-old Ngog, who scored 19 goals in 94 games during his three years at Liverpool, joined Championship club Bolton for £4million in 2011.