While in Canada, Ratchford played Marvel Comic book character Banshee in the live action TV super hero film Generation X. Ratchford also starred in a series of Canadian Crispy Crunch candy bar commercials.{{citation needed|date=April 2016}}
When he relocated to Hollywood, California, he played a sexual predator on an episode of NYPD Blue and two episodes of The Practice, as well as the vampire Lyle Gorch in the Buffy the Vampire Slayer episodes "Bad Eggs" and "Homecoming" before being cast on Cold Case. On Cold Case, he played detective Nick Vera.
| Year | Title | Role | Notes | | 1985 | Check It Out | Brandon | television debut
Episode: "Skip to the Loo" |
| 1986 | Walt Disney's Wonderful World of Color | Todd | Episode: "Young Again" |
| 1986 | As Is | Pickup #1 | Television Movie |
| 1986 | Hangin' In | Hit Man | Episode: "Hit Man Kate" |
| 1986 | Easy Prey | Billy | Television Movie |
| 1986 | The Truth About Alex | Dutch | Television Movie |
| 1986-1987 | The Lawrenceville Stories | Charley DeSoto | Television Miniseries; 3 episodes |
| 1986-1990 | The Campbells | Ox | 8 episodes; recurring role |
| 1987 | American Playhouse | Charley DeSoto | Episode: "The Prodigious Hickey" |
| 1987 | CBS Schoolbreak Special | Luke | Episode: "The Day They Came to Arrest the Book" |
| 1987 | Night Heat | Doyle | 2 episodes |
| 1988 | T and T | Bob Douglas | Episode: "The Drop" |
| 1988 | Diamonds | unknown | Episode: "Man with a Gun" |
| 1988 | Alfred Hitchcock Presents | Tom | Episode: "Fogbound" |
| 1988 | War of the Worlds | Student | Episode: "Goliath Is My Name" |
| 1988 | 9B | Frankie Mitchell | 2 episodes |
| 1989 | Street Legal | Mark Leeson | Episode: "Brotherhoods" |
| 1991 | Counterstrike | Jeremy | Episode: "Hidden Assets" |
| 1991 | Rin Tin Tin: K-9 Cop | unknown | Episode: "Light at the End of the Tunnel" also known as "Katts and Dog" |
| 1991 | Top Cops | Tom Kennedy | Episode: "Tom Kennedy/Eddie Perez and Raul Alviso/Danny Miller" |
| 1992 | A Savage Christmas: The Fall of Hong Kong | Fred Reich | Television Documentary |
| 1992 | Top Cops | Jim Gorry | Episode: "Freddie Williams/Jim Gorry/Bruno Pezzulich" |
| 1992 | Beyond Reality | unknown | Episode: "Master of Darkness" |
| 1992 | Secret Service | Demarco | Episode: "Curiosity Killed the Cat/Murder, He Broke" |
| 1992-1996 | X-Men | Banshee/Sean Cassidy (voice role) | 15 episodes; recurring role |
| 1993 | Secret Service | Lombardi | Episode: "Brothers in Arms" |
| 1993 | Matrix | Eddie Mayberry | Episode: "Death and Taxes" |
| 1993 | Street Legal | Jeffrey Sinclair | 2 episodes |
| 1993 | The Kids in the Hall | Rookie | Episode: "#4.10" |
| 1994 | Getting Gotti | Harvey Sanders | Television Movie |
| 1994 | RoboCop | J.J. Biddle | Episode: "When Justice Fails" |
| 1994 | Small Gifts | Evan | Television Movie
Nominated - Gemini Award for Best Lead Actor in a Dramatic Program or Miniseries (1996) |
| 1994-1995 | The Busy World of Richard Scarry | unknown (voice role) | 4 episodes; recurring role |
| 1995 | The Series | Travis | Episode: "Blood Money" |
| 1995 | The Shamrock Conspiracy | Johnny McQueen | Television Movie |
| 1995 | TekWar | Logan | Episode: "Cyberhunt" |
| 1995 | Convict Cowboy | Bob | Television Movie |
| 1995 | Where's the Money, Noreen? | Satterfield | Television Movie |
| 1996 | Generation X | Sean Cassidy | Television Movie |
| 1996 | Moonshine Highway | Dwayne Dayton | Television Movie |
| 1996 | Defenders of the Realm | Smoke (voice role) | Episode: "Old Friends Never Die" |
| 1997 | Home Invasion | Raymond | Television Movie |
| 1997 | The Sentinel | Artie Parkman | Episode: "The Girl Next Door" |
| 1997 | Aaahh!!! Real Monsters | Shadowy Figure (voice role) | Episode: "Spy vs. Monster/Misery Date" |
| 1997 | Peacekeepers | Sergeant Conrad Bitner | Television Movie |
| 1997 | The Practice | Gibbons | Episode: "Hide and Seek" |
| 1998 | The Outer Limits | Sergeant Adam Sears | Episode: "Relativity Theory" |
| 1998 | Brooklyn South | Robert Standley | Episode: "Doggonit" |
| 1998 | Wings of Gold | Seaton Palmer | Episode: "Not in My Backyard" |
| 1998 | Buffy the Vampire Slayer | Lyle Gorch | 2 episodes |
| 1999 | JAG | Lewis Beecham | Episode: "Rivers' Run" |
| 1999 | Turks | Tony | Episode: "Lend My Your Ears" |
| 1999 | Walker, Texas Ranger | Maxwell | Episode: "Brothers in Arms" |
| 1999 | The Legacy | James "Jimmy" Boyle | Episode: "Brother's Keeper" |
| 2000 | The Magnificent Seven | Handsome Jack Averal | Episode: "Obsession" |
| 2000 | The Wild Thornberrys | Alligator (voice role) | Episode: "Time Flies" |
| 2000 | Blacktop | Mechanic | Television Movie |
| 2001 | The Sports Pages | unknown | Television Movie; segment "The Heidi Bowl" |
| 2001-2003 | Blue Murder | Detective Jack Pogue | series regular; 39 episodes
Nominated - Gemini Award for Best Lead Actor in a Continuing Dramatic Role (2001, 2003) |
| 2002 | The Practice | Gavin Brown | Episode: "The Test" |
| 2002 | Crime Scene Investigation | Tommy Sconzo | Episode: "Primim Non Nocere" |
| 2002 | NYPD Blue | Darryl Marquette | Episode: "Low Blow" |
| 2003-2010 | Cold Case | Nick Vera | series regular; 156 episodes |
| 2008 | Comanche Moon | Charlie Goodnight | Television Miniseries; Episode: "#1.3" |
| 2010 | One Angry Juror | Don Burston | Television Movie |
| 2011 | Shameless | Detective Bernero | Episode: "Father Frank, Full of Grace" |
| 2011 | Hawaii Five-0 | Chet | Episode: "Alaheo Pau'ole" |
| 2012 | Perception | Detective Hammond | Episode: "Pilot" |
| 2012 | It's Always Sunny in Philadelphia | Detective | Episode: "The Maureen Ponderosa Wedding Massacre" |
| 2015 | The Mentalist | George Hoilday | Episode: "Little Yellow House" |
| 2015 | Bones | ATM | Episode: "The Eye in the Sky" |
| 2015 | Longmire | Rett Jacky | Episode: "War Eagle" |
| 2015 | NCIS | Baltimore Police Detective Ramsey Malone | Episode: "Day in Court" |
| 2016 | Workaholics | Frank | Episode: "Always Bet on Blake" |
| 2016 | Chicago P.D. | Jim | Episode: "300,000 Likes" |
| 2017 | New Orleans | Richard Marino | Episode: "NOLA Confidential" |
| 2017 | Beyond Borders | Boris | Episode: "The Ripper of Riga" |
| 2018 | Taken | Detective Lyons | Episode: "Absalom" |