Below is a list of runners who have reached 100 marathons in 2020 along with the event and date this milestone was reached.
| Runner | Event | Date |
|---|---|---|
| Carly Watson | Saturn Cheeky Little Pop Up Run | 13-Dec-20 |
| Richard Lisle | Phoenix Assemble Ironran | 13-Dec-20 |
| Kim Freeman | Band Of Runners Festive Marathon | 06-Dec-20 |
| Andy Bristow | November Nightmare day 4 | 04-Nov-20 |
| Sonja Farish | Brathay 10in10 day 10 | 01-Nov-20 |
| Andy Wood | GRIM Hubble Bubble | 31-Oct-20 |
| Colin Johnstone | GRIM Hubble Bubble | 31-Oct-20 |
| Diane Morris | Brathay 10in10 day 2 | 24-Oct-20 |
| Graeme Chamberlin | Endurancelife CTS Suffolk | 24-Oct-20 |
| Stuart Mills | Beachy Head | 24-Oct-20 |
| Tony Conway | QE Spring Marathon | 18-Oct-20 |
| Brent Crowle | Phoenix Back to the 80s | 17-Oct-20 |
| Neil Addington | Roman River Trail | 11-Oct-20 |
| Suzanne Cormack | GBC Clover | 04-Oct-20 |
| Cheryl Broas | Saturn Nearly But Not Quite London | 04-Oct-20 |
| Jay MacDonald | SRC Ousden Owl | 03-Oct-20 |
| Mary Taylor | SVN Tolkien Challenge | 26-Sep-20 |
| Hilary Wharam | Sir Titus Trot Summer day 2 | 13-Sep-20 |
| Ian Brazier | Phoenix Party Train II | 13-Sep-20 |
| Martin Sanderson | SVN 20in20 in 2020 day 20 | 10-Sep-20 |
| Martin Storer | SVN 20 in 20 in 2020 day 16 | 06-Sep-20 |
| John Whitcher | SVN 20 in 20 in 2020 day 10 | 31-Aug-20 |
| John Strougler | SVN 20 in 20 in 2020 day 3 | 24-Aug-20 |
| Jo Gwynne | Phoenix Odin's Spear | 16-Aug-20 |
| Michelle Haresnape | Phoenix Odin's Spear | 16-Aug-20 |
| Dean Longman | SVN Dragon Run | 15-Aug-20 |
| Tracy Fox | Phoenix Hercules Labour Four | 09-Aug-20 |
| Ray Gurvitz | Phoenix Hercules Labour Three | 08-Aug-20 |
| Rob Marshall | SRC Quackers Run Day 1 | 01-Aug-20 |
| James Graham | SVN Very British Challenge | 26-Jul-20 |
| Sarah Marzaioli | Moyleman | 15-Mar-20 |
| Justine Flett | SVN Funky Pants Challenge | 08-Mar-20 |
| Ann Holmes | Golden Fleece Circuit | 07-Mar-20 |
| Wayne Greaves | Thames Spring Meander | 07-Mar-20 |
| George McDonough | SVN Bookday Challenge | 07-Mar-20 |
| James Patterson | SVN Leap Year Challenge | 29-Feb-20 |
| Ian Sloan | Running Miles Another Run Bites The Dust | 27-Feb-20 |
| Rosie Williams | SVN Marathon Day | 26-Feb-20 |
| Tony Stevenson | Phoenix 100MC AGM Marathon | 22-Feb-20 |
| Mike Gwynne | Phoenix Elven Blue Run | 08-Feb-20 |
| Adam Lowe | Marrakech | 24-Jan-20 |
| Matthew Hearne | Country to Capital | 11-Jan-20 |