Wales toiled to three crucial Group Four points at the Millennium Stadium but it could have been a much more comfortable second half for the majority of the 12,500 crowd.
West Ham striker Bellamy had been Wales' constant inspiration, even if Liechtenstein goalkeeper Peter Jehle did his best to ruin his night.
He turned one Bellamy shot onto the crossbar, blocked his first-half spot-kick and then produced a miracle save from a point-blank effort from the 29 year-old.
Wales eventually took the points thanks to David Edwards' first goal for his country (42) and a deflected header from substitute Ched Evans (80).
The win will have increased confidence for an infinitely more difficult match against Germany in Monchengladbach on Wednesday.
Wales boss John Toshack retained Ashley Williams and Craig Morgan in central defence, and there was no place at full-back for Sam Ricketts - while Sam Vokes started up front.
It meant that fit-again centre-half James Collins was a substitute, while Wolves youngster Wayne Hennessey had recovered from illness to keep his place in goal.
Vokes partnered Bellamy in attack, the West Ham man returning to play his first game for his country in 11 months.
Bellamy was quick to utilise the right flank, Jason Koumas the left and Simon Davies adding support - and they started well.
Bellamy almost scored after just three minutes when he cut in from the right to see his angled drive pushed on to the bar by Jehle.
Koumas' header from the rebound was also saved, the Wigan man then seeing a 20-yarder fly just wide.
Liechtenstein defended in depth but were quick on the break and on more than one occasion caught Wales short-handed at the back.
Michele Polverino hit one drive wide of the far post after a sortie up field.
Martin Buchel was booked for kicking the ball away from a free-kick - but with Liechtenstein defending well, Wales' approach work too slow.
Bellamy worked himself into a good position just outside the box and saw a low drive flash inches wide.
The Welsh began to look lethargic and lacking in cohesion, resorting to long balls from the back.
Delivery from the flanks was poor or over-hit - and when Koumas eventually got into a good position to deliver a pass into the six-yard box, Vokes somehow managed to miss his connection from a yard out.
Eventually Wales managed a move of pace and accurate passing, and they took the lead. Chris Gunter's clever chip down the right sent Davies away, and his cross was swept into the net off a post by David Edwards - his first goal for his country.
Bellamy then saw a shot pushed away by Jehle, before missing a 43rd-minute penalty after Buchel had tripped Gareth Bale.
It was the third successive spot-kick Wales have missed in this World Cup group.
Bellamy's low shot was scrambled away by Jehle to his left.
Five minutes into the second period, Wales sent on Evans in place of Vokes to provide a more forceful approach against Liechtenstein's defensive pairing of Fabio D' Elia and Martin Stocklasa.
Soon afterwards, Carl Robinson was sent on to win his 50th cap in place of Carl Fletcher.
Full-backs Gunter and Bale were both linking up on the flanks more and supplying crosses, if not always accurately.
Koumas forced Jehle into another plunging save with a 20-yarder, and then fired over from 10 yards.
Liechtenstein took off full-back Marco Ritzberger and sent on Mathias Christen to play up front.
Jehle then made a stunning reflex save to push over a close-range Bellamy shot following a Davies chip.
Polverino was booked for a foul on Koumas and was fortunate to escape a red when he pulled Bellamy back after the little striker had got away from him. Referee Thomas Vejlgaard saw the incident but opted to play advantage.
Bellamy was booked for a foul on Polverino, who was soon to limp off and be replaced by Ronny Buchel.
Within seconds, Wales got their second.
Davies curled in a corner, and Evans rose to send in a powerful header that deflected into the net off Frick.
That was the cue for Bellamy to be withdrawn, allowing club-mate Collins his first match for 11 months after knee surgery.