Henley carded a final-round 69 to finish with four straight rounds in the 60s and set a new Georgia Amateur scoring record at 270.
Past Amateur champion David Noll Jr. of Dalton placed third at 8-under 272, two strokes back of Henley.
Two Augustans, Josh Gregory and second-round leader Jeff Knox, tied for fourth at 1-under 279. Jay Moseley of Bainbridge fired the low round of the day, a 5-under 65, to move up to a tie for sixth place at even par with Dave Womack of McDonough.
Three players - Nate Balanis of Valdosta, Jeff Belk of Marietta and 1995 Amateur champion Adam Thomas of Baxley - tied for eighth at 2-over 282.
English and Henley, who are roommates and members of the golf team at the University of Georgia, began the day knotted at 9-under, but the tie was broken on No. 4 when English carded his first birdie of the day, hitting his approach to three feet on the 486-yard, par-4.
Henley, meanwhile, chipped over the green and had to settle for bogey.
English picked up another stroke with a birdie at No. 5, then extended his lead to four shots with another Henley bogey at No. 7.
Like English's comeback charge on the back nine during Saturday's round, Henley was not going away quietly, especially with a large crowd of hometown supporters following his final group.
He chipped away at his deficit with three, 20-foot-plus birdie putts on holes 9, 11 and 12.
English pocketed another birdie at No. 10, but suffered his first bogey of the day at No. 13 after driving over the green and three-putting.
That dropped him back to 11-under, just one stroke ahead of Henley.
On the course's longest hole, the 629-yard 15th, English had just hit his second shot out of bounds when the horns blew, indicating suspension of play due to bad weather in the area.
Play was halted for two hours and 11 minutes - from 1:40 to 3:51 p.m.
After the delay, English wound up with double bogey on the hole and Henley missed a three-foot birdie attempt that would have given him a two-shot lead with three holes to play.
With the comeback par putt, however, Henley took the outright lead for the first time in the round.
"That was certainly a big momentum swing," Henley said. "I knew at that point if I played solid all the rest of the way, I'd have a chance."
Still leading by one going into the par-3 18th, Henley hit his tee shot 20 feet from the hole, which was located up on the back ridge of the green.
English's shot also landed on the ridge, but rolled off towards the front of the green.
His second shot slid several feet past, allowing Henley a two-putt for the victory.
English parred 18 to finish at even-par 70 for the round, his only round of the tournament not under par.
Noll was the only other player besides Henley to fire four rounds in the 60s, carding a final-round 69 with just one bogey on the day.
"If I didn't know a lot about this course, I don't think I would've come away with it," Henley said. "Harris is a tough guy to beat. I've been trying to beat him since I was 11.
"This show how hard I've been working; it really means a lot," he continued.
Not only did Henley fire a new tournament low, he also becomes the first Georgia Amateur champion to win on his home course in nearly 40 years.
Randy Strozier Jr. of Augusta captured the title at Augusta Country Club in 1969.
Idle Hour's course played to 6,671 yards and a par of 70.
The Georgia Amateur Championship is conducted by the Georgia State Golf Association and brings together 156 of the state's best male amateur golfers for the prestigious state title first won by Bobby Jones in 1916.
The Championship format was 72 holes of stroke play over four days.
The field was cut to the low 70 and ties after the second round, with the cut line falling at 10-over 150 and 75 players advancing to the weekend.
Founded in 1916, the Georgia State Golf Association (GSGA) received its official charter on June 24, 1924. Since that date, the GSGA has grown to one of the largest state amateur golf associations in the country, with over 365 member clubs and 85,000 individual members. With a mission to promote and preserve amateur golf in the state of Georgia, GSGA offers a computerized handicapping service, course rating and measuring, and annually conducts a full schedule of statewide competitions for men and women of all age groups. Other services include a summer-long junior sectional program, award-winning Golf Georgia magazine, membership recognition and rewards programs and a charitable foundation administering two college scholarship programs.
Georgia State Golf Association
87th Annual Georgia Amateur Championship Idle Hour Club, Macon July 10-13, 2008
Final Results
Par 70
Place Name Rd. 1 Rd. 2 Rd. 3 Rd. 4 Score To Par
1 Russell Henley, Macon 67 68 66 69 270 -10
2 Harris English, Thomasville 66 69 66 70 271 -9
3 David Noll Jr., Dalton 68 68 67 69 272 -8
T4 Jeff Knox, Augusta 64 70 73 72 279 -1
T4 Josh Gregory, Augusta 68 70 69 72 279 -1
T6 Dave Womack, McDonough 71 65 71 73 280 Even
T6 Jay Moseley, Bainbridge 71 71 73 65 280 Even
T8 Adam Thomas, Baxley 69 73 68 72 282 2
T8 Jeff Belk, Marietta 70 71 73 68 282 2
T8 Nate Balanis, Valdosta 69 72 74 67 282 2
T11 Jarod Trammell, Jasper 72 69 71 71 283 3
T11 Mark Strickland, Woodstock 72 70 67 74 283 3
T11 Robert Sheats, Atlanta 66 72 69 76 283 3
T14 Oliver West, Kennesaw 72 69 73 70 284 4
T14 Peter Persons, Macon 71 71 70 72 284 4
T16 Chris Smith, Alpharetta 68 74 71 72 285 5
T16 Danny Nelson, Savannah 71 75 67 72 285 5
T16 Tim Schaetzel, Atlanta 66 71 71 77 285 5
T19 Alex Castro, Alpharetta 73 73 70 71 287 7
T19 Billy Shida, Duluth 70 71 74 72 287 7
T21 Griff Moody, Alpharetta 70 73 75 70 288 8
T21 Jack Hall, Sea Island 70 70 74 74 288 8
T21 Wade Binfield, Fayetteville 78 71 66 73 288 8
24 Greg Kennedy, Duluth 71 74 71 73 289 9
T25 Chris Hall, Kennesaw 71 75 72 72 290 10
T25 Ryan Willis, Alpharetta 77 73 71 69 290 10
T27 Bryan Miller, Rocky Face 70 73 76 72 291 11
T27 Ryan Parnell, Atlanta 74 68 71 78 291 11
T29 Benjamin Kishigian, Warner Robins 76 72 69 76 293 13
T29 Jorge Cora, Atlanta 72 74 72 75 293 13
T29 Philip Verlander, Decatur 74 70 75 74 293 13
T32 Lee Dennis, Comer 73 77 68 76 294 14
T32 Trent Erb, Atlanta 71 72 75 76 294 14
T32 William Meason III, Alpharetta 75 70 72 77 294 14
T35 Alex Frankel, Atlanta 76 71 72 76 295 15
T35 Bob Royak, Alpharetta 68 73 78 76 295 15
T35 Brent Paul, Midland 74 74 73 74 295 15
T35 Coleman Calhoun, Vidalia 70 72 79 74 295 15
T35 Matt Bernstein, Alpharetta 73 71 75 76 295 15
T35 Ollie Schniederjans, Powder Springs 73 72 77 73 295 15
T35 Wills Smith, Savannah 72 71 75 77 295 15
T42 Doug Stiles, Athens 73 71 78 74 296 16
T42 Michael Standard, McDonough 68 73 80 75 296 16
T42 Rob Bennett, Augusta 74 75 75 72 296 16
T42 William Mitchell, Roswell 75 73 73 75 296 16
T46 Michael Saari, Lilburn 71 72 80 74 297 17
T46 Ryan Wilson, Albany 73 73 80 71 297 17
T46 Trey McQuaig, Valdosta 78 70 77 72 297 17
T49 Alex Jones, Woodstock 73 71 76 78 298 18
T49 Blake Stark, Canton 77 70 75 76 298 18
T49 Jack Larkin, Atlanta 76 69 75 78 298 18
T49 John Gregory Joseph, Valdosta 72 77 75 74 298 18
T49 Stephen Welsh, Macon 72 74 75 77 298 18
T54 Bill Brown, Dublin 75 75 75 74 299 19
T54 Brent Landry, Woodstock 73 74 76 76 299 19
T54 Brian Carter, Evans 74 71 76 78 299 19
T54 Cory Hurley, Atlanta 73 73 74 79 299 19
T54 Hudson Keener, Dalton 73 73 76 77 299 19
T54 John Stembridge, Norcross 72 74 77 76 299 19
T54 Sam Braver, Roswell 71 74 74 80 299 19
T61 Anders Albertson, Woodstock 72 73 76 79 300 20
T61 Chris Waters, Evans 72 73 77 78 300 20
T61 Pete Abernathy, Atlanta 73 77 77 73 300 20
T61 Sandy Burgess, Macon 76 69 79 76 300 20
T65 Hal Greer, Macon 73 71 77 80 301 21
T65 Keith Holmes, Macon 76 74 70 81 301 21
T67 Cory Crump, Peachtree City 70 77 78 79 304 24
T67 Jamie Kiely, Alpharetta 77 72 76 79 304 24
T69 Edwin Wolfe, Warner Robins 73 76 80 77 306 26
T69 Tom Parker, Suwanee 76 72 78 80 306 26
71 Gary Melampy, Norcross 75 73 77 83 308 28
72 Craig Taylor, Albany 75 75 80 80 310 30
73 Dave Sexton, Suwanee 73 76 78 84 311 31
74 John Skeadas III, Savannah 71 78 84 81 314 34
75 Scott Davenport, Marietta 75 74 79 WD