The five-time Ryder Cup star from Northern Ireland closed with a 1-over 73 at the Tomson Shanghai Pudong Golf Club to hold off the Netherlands' Robert Jan Derksen.
Clarke's 18th hole heroics came after he made three late bogeys to erase a two-shot lead. He finished at 8-under 280 for his first title since the 2003 WGC-NEC Invitational.
Since that victory almost five years ago, it has been Clarke's personal life that has garnered headlines.
His wife, Heather, died in 2006 following a lengthy and well-publicized bout with breast cancer that forced Clarke to frequently withdraw from tournaments to be with his family, which includes two sons.
Clarke committed to play in the Ryder Cup just one month later and guided the Europeans to an emotional landslide victory.
His win on Sunday was a relief.
'With everything that has gone on these past few years, to spiral down the world rankings and keep working and people writing me off, it's just nice to come back and play the way I know I can,' said Clarke.
Derksen, after trailing Clarke by a stroke overnight and playing against him in the final pairing, also shot a 73 Sunday to end at 7-under 281. He was tied for the lead heading to the 18th hole, but managed only a par.
'I can't be negative after today,' said Derksen, who was seeking his third European Tour win and first in three years. 'I thought it was a great battle.'
Clarke's bogey at the 14th hole -- coupled with a Derksen double-bogey -- left the Ulsterman holding a two-stroke advantage. But Clarke went on to make bogey at the 16th and 17th holes to erase that seemingly comfortable lead.
'Unfortunately, I got ahead of myself with about five holes to play and was thinking about things that have happened in the past with Heather and the boys and I just lost my concentration,' said Clarke.
The lapse led to some 'silly mistakes,' Clarke said, but those errors were erased with one long putt at the 18th -- which helped him finally get rid of a pesky Derksen.
'To hole a putt from that length -- there's always a huge amount of luck involved as well,' said Clarke. 'When they go in like that sometimes it's a bit of destiny.'
Clarke's 280 total tied for the second-highest winning score this season on the European Tour international schedule. Only James Kingston's 284 at the South African Airways Open in December was worse. Trevor Immelman shot a 280 to win the Masters two weeks ago.
'Sometimes things are meant to happen, sometimes not,' said Clarke. 'I guess today was my day.'
Italy's Francesco Molinari (69), Chinese Taipei's Lin Wen-Tang (72) and England's Robert Dinwiddie (74) tied for third place at five-under 283.
World No. 13 Henrik Stenson of Sweden, the highest-ranked player in the field, closed with a solid four-under 68 to take sixth place at 4-under 284.
Two-time U.S. Open winner Retief Goosen (73) finished at 1-under 287, while former world No. 1 and two-time British Open champion Greg Norman (71) ended at even-par 288 in a rare start.
Liang Wen-Chong was China's top finisher at even-par.