Porter, who will also be an outfield instructor, joins the Nationals after spending the 2010 season on the D-backs' coaching staff, first as third-base coach before being elevated to bench coach upon Kirk Gibson being named Arizona's manager on July 3.
Porter returns to the NL East, where he served as the Marlins' third-base coach and outfield/baserunning instructor from 2007-09. While in Florida, Porter worked extensively with current Nationals left fielder Josh Willingham.
Willingham isn't the only member of the Nationals who have dealt with Porter in the past. Last offseason, general manager Mike Rizzo interviewed Porter for the managerial job that eventually went to Jim Riggleman.
During his years as a Minor League field coordinator in the Cardinals system, Riggleman often dealt with Porter because the Marlins and Cardinals share the same Spring Training facility in Jupiter, Fla.
"I've known Bo for a long time," Riggleman said. "He has a great respect for the game. He has a real good work ethic. He preaches attention to detail and appreciates the little things in the game. He is right on board with what we are trying to do."
In other news, the Nationals officially announced that bench coach John McLaren, pitching coach Steve McCatty, hitting coach Rick Eckstein, first-base coach Dan Radison and bullpen coach Jim Lett will return next season. The news was first reported by MLB.com in October.
"My feelings all along was to keep our coaching staff together," Riggleman said. "[Our record wasn't good this past season], but don't blame the coaching staff. Our coaches did a great job and they will continue to do a great job. The work the coaches put in, I couldn't ask for anything more."
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on twitter -- @washingnats. This story was not subject to the approval of Major League Baseball or its clubs.