Stumbling Wales are grateful for PS80m man's intervention.
Wales trailed to a fifth-minute penalty from Ildefons Lima as Andorra, ranked 199 in the world, scored their first goal in competitive football for four years.
But PS80m Real Madrid star Bale equalised with a 22nd minute header before grabbing a dramatic winner nine minutes from time with a wonderful 25-yard free-kick.
Coleman had hinted he would use the Real Madrid winger in a more central role against opponents ranked 199 in the world and without a competitive victory for 10 years.
But he handed a start to out-offavour Charlton striker Simon Church and Bale was expected to start in a 4-3-3 formation on the right with Swansea's Neil Taylor on the left.
The 3G artificial surface had generated plenty of headlines in the build-up to the game and it was clearly far from perfect, but Wales fashioned the first chance inside 45 seconds.
Aaron Ramsey found Chris Gunter down the right with a raking pass and the full-back forced Andorra goalkeeper Ferran Pol into a smart save at the near post.
But Wales were stunned after five minutes when Andorra scored their first competitive goal since September 2010 courtesy of a controversial penalty.
Ildefons Lima flicked on a long throw and Neil Taylor was adjudged to have fouled Ivan Lorenzo, not by the referee but by one of the officials behind the goal. Lima sent Wayne Hennessey the wrong way from the spot to spark wild celebrations among the Andorra team.
Wales equalised on 22 minutes when Ben Davies crossed from the left and Bale beat his marker and head firmly into the corner.
Bale's 13th goal for his country settled Wales and Ramsey cut into the area to send Andorra alarm bells, ringing but the hosts just managed to smother the danger.
The Real Madrid star was dropping deep trying to influence matters, but Andorra were not overawed and in burly striker Gabriel Riera had a focal point for crosses.
Riera troubled Ashley Williams from one such delivery and James Chester had to react quickly to prevent a goal-scoring opportunity. Wales were struggling to penetrate a tight Andorra defence, but the same Davies-Bale combination which had worked for the goal almost paid off again close to halftime.
Davies swung over another excellent cross, but this time Bale was eased off the ball.
Joe Allen was booked in the closing stages of the half after becoming involved in a tussle with Andorra's Edu Peppe.
Andorra must have feared the worst when Bale lined himself up over a 57th minute free-kick after the Madrid man had been pushed to the ground.
Bale's shot dipped in front of goalkeeper Pol who just about managed to push the ball to safety. But Wales picked up the loose ball and Bale crossed into the centre where Andy King rose well, but could not divert his header goalward.
Coleman sent on Joe Ledley for Church after 62 minutes and Wales were sending men forward in search of a second while being at risk of being exposed on the break.
Williams almost capitalised on a Bale cross, but he was denied by brave Andorra defending while claims for a penalty for handball were waved away by Slovenian referee Slavko Vincic.
Wales were forcing plenty of setpieces even if chances were not in plentiful supply.
Bale was felled to win a free-kick which was saved by Pol in the Andorra goal. But he was given a second chance as Riera had raced out too quickly and this time the winger curled a magnificent 25-yard effort into the corner of Pol's net.
MATCH FACTS ANDORRA: Pol, Garcia Miramontes, Lima, Maneiro Ton, Rubio, Vales Peppe (Vieira de Vasconcelos 52), Ayala Diaz (Sanchez Soto 86) Martinez Alejo (Sonejee 83), Lorenzo Roncero, Riera. Subs (not used): Josep Anton Gomez, Rodrigues, Clemente, Moreno.
Booked: Peppe, Lorenzo Roncero, Maneiro Ton, Vieira de Vasconcelos Riera, Vales.
Goal: Lima 6 pen. WALES: Hennessey, Gunter, Neil Taylor, Chester, Davies Ashley Williams, Allen, King (George Williams 76) Ramsey (Huws 90), Bale, Church (Ledley 62). Subs (not used): Fon Williams, Dummett, Gabbidon, Vaughan, Lawrence Jonathan Williams, Jake Taylor, John, Letheren. Booked: Allen, Church.
Goals: Bale 22, 81. Attendance: 10, 000 Referee: Slavko Vincic (Slovenia).
Gareth Bale scores the second of his two goals to give Wales victory Adam Davy