I-20 is four lanes in much of the state. In the Atlanta metro area, the highway ranges from six lanes in the most outlying counties to 10 lanes in downtown Atlanta.
Like the rest of Georgia's interstates, I-20 has an unsigned state highway designation: State Route 402.
Until 2000, the state of Georgia used the sequential interchange numbering system on all of its Interstate Highways. The first exit on each highway would begin with the number "1" and increase numerically with each exit. In 2000, the Georgia Department of Transportation switched to a mileage-based exit system, in which the exit number corresponded to the nearest milepost.[7] [8]
| County | Location | Exit # | Destinations | Notes |
| Old | New |
| Haralson | | 1 | 5 | SR 100 – Tallapoosa, Bowdon | |
| 2 | 9 | Waco Road | |
| Carroll | | 3 | 11 | US 27 – Bremen, Carrollton | |
| 4 | 19 | SR 113 – Carrollton, Temple | |
| Villa Rica | 5 | 24 |  SR 61 / SR 101 – Carrollton, Villa Rica | |
| Douglas | | 6 | 26 | Liberty Road – Villa Rica | |
| 7 | 30 | Post Road | |
| Douglasville | 8 | 34 | SR 5 – Douglasville | |
| 9 | 36 | Chapel Hill Road | |
| 10 | 37 | SR 92 (Fairburn Road) – Douglasville | |
| 11 | 41 | Lee Road – Lithia Springs | |
| 12 | 44 | SR 6 (Thornton Road) – Austell | |
| Cobb | | 13 | 46 | Six Flags Drive, Riverside Parkway | Westbound is split into Exit 46A (Old Exit 13A — Riverside Parkway) and Exit 46B (Old Exit 13B — Six Flags Drive) |
| 13C | 47 | Six Flags Parkway | Westbound exit and eastbound entrance only |
| Fulton | | 14 | 49 | SR 70 (Fulton Industrial Boulevard) | |
| Atlanta | 15A-B | 51A-B | I-285 – Macon, Montgomery, Chattanooga, Greenville | |
| 16A-B | 52A-B | SR 280 (Hamilton E. Holmes Drive) | Eastbound is signed Exit 52 (Old Exit 16). |
| 17 | 53 | SR 139 (Martin Luther King Jr. Drive) | |
| 18 | 54 | Langhorn Street | Westbound exit and eastbound entrance |
| 19 | 55A | Lowery Boulevard, West End | |
| 20 | 55B | Atlanta University Center, Lee Street | Westbound exit and eastbound entrance only. |
| 21 | 56A | McDaniel Street | Eastbound exit and westbound entrance |
| 22 | 56B | Windsor Street to Spring Street, Turner Field | |
| 23 | 57 |  I-75 / I-85 – Macon, Montgomery, Chattanooga, Greenville | |
| 24 | 58A | Capitol Avenue | Westbound exit and eastbound entrance |
| 25 | 58B | Hill Street | Westbound exit and eastbound entrance |
| 26 | 59A | Boulevard | |
| 27 | 59B | Memorial Drive, Glenwood Avenue | Eastbound exit and westbound entrance |
| 28A-B | 60A-B | US 23 (Moreland Avenue) | Westbound exit is signed Exit 60 (Old Exit 28) |
| Dekalb |
| 29 | 61A | Maynard Terrace | Eastbound exit and westbound entrance |
| 30 | 61B | SR 260 (Glenwood Avenue) | |
| 31 | 62 | Flat Shoals Road | Eastbound exit and westbound entrance |
| 32 | 63 | Gresham Road, Flat Shoals Road | Signed Gresham Road eastbound and Flat Shoals Road westbound |
| 33 | 65 | SR 155 (Candler Road) – Decatur | |
| 34 | 66 | Columbia Drive | Eastbound exit and westbound entrance |
| 35A-B | 67A-B | I-285 – Macon, Chattanooga, Greenville | Eastbound is signed Exit 67 (Old Exit 35) |
| 36 | 68 | Wesley Chapel Road to Spanfinger Road | |
| 37 | 71 | Panola Road | |
| 38 | 74 | Evans Mill Road, Lithonia Industrial Boulevard – Lithonia | |
| 39 | 75 |  US 278 / SR 124 (Turner Hill Road) | West end of US 278 concurrency |
| Rockdale | | 40 | 78 | Sigman Road | |
| Conyers | 41 | 80 | West Avenue – Conyers | |
| 42 | 82 |  SR 20 / SR 138 – Conyers, Monroe | |
| 43 | 84 | SR 162 (Salem Road) | |
| Newton | | 44 | 88 | Almon Road – Porterdale | |
| Covington | 45 | 90 | US 278 east – Covington, Oxford | |
| 45A | 92 | Alcovy Road | |
| 46 | 93 | SR 142 – Hazelbrand, Oxford, Covington | |
| 47 | 98 | SR 11 – Monroe, Monticello | |
| 48 | 101 | US 278 | |
| Morgan | | 49 | 105 | Newborn Road – Newborn, Rutledge | |
| 50 | 113 | SR 83 – Madison, Monticello | |
| 51 | 114 |  US 129 / US 441 – Madison, Eatonton | |
| 52 | 121 | Seven Islands Road – Buckhead | |
| Greene | | 53 | 130 | SR 44 (Lake Oconee Parkway) – Eatonton | |
| Siloam | 54 | 138 |  SR 15 / SR 77 – Siloam, Union Point, Sparta, Greensboro | |
| Taliaferro | | 55 | 148 | SR 22 – Crawfordville, Sparta |
| Warren | | 56 | 154 | US 278 – Warrenton, Washington | |
| 57 | 160 | Cadley Norwood Road – Norwood | |
| 58 | 165 | SR 80 – Camak | |
| McDuffie | | 59 | 172 |  US 78 / SR 17 – Thomson, Washington | |
| 60 | 175 | SR 150 | |
| Columbia | | 61 | 183 | US 221 – Harlem | |
| 62 | 190 | SR 388 – Grovetown | |
| Evans | 63 | 194 | SR 383 (Belair Road, Dyess Parkway) – Evans | |
| Richmond | Augusta | 63A | 195 | Wheeler Road | |
| 64A-B | 196A-B |  I-520 / SR 232 (Bobby Jones Expressway) | |
| 197 | Walton Way Extension | Westbound exit and eastbound entrance |
| 65 | 199 | SR 28 (Washington Road) – Augusta | |
| 66 | 200 | SR 104 (River Watch Parkway) – Augusta | |