Nationals Roster & Staff
Transactions
| Date | Transaction |
| 06/30/15 | Washington Nationals signed SS Max Schrock. |
| 06/30/15 | Washington Nationals signed 2B Jake Jefferies. |
| 06/30/15 | Washington Nationals signed 2B Melvin Rodriguez. |
| 06/29/15 | Washington Nationals signed free agent RHP Carlos Pena to a minor league contract. |
| 06/29/15 | Washington Nationals optioned SS Wilmer Difo to Harrisburg Senators. |
| 06/28/15 | Washington Nationals recalled Wilmer Difo from Harrisburg Senators. |
| 06/27/15 | Washington Nationals signed RHP Andrew Lee. |
| 06/27/15 | Washington Nationals signed 3B Dalton DiNatale. |
| 06/26/15 | Washington Nationals signed RHP Matt Pirro. |
| 06/26/15 | Washington Nationals placed 2B Anthony Rendon on the 15-day disabled list retroactive to June 25, 2015. Left quadriceps strain |
| 06/26/15 | Washington Nationals selected the contract of 2B Emmanuel Burriss from Syracuse Chiefs. |
| 06/26/15 | Washington Nationals transferred LF Reed Johnson from the 15-day disabled list to the 60-day disabled list. Torn tendon in his left calf |
| 06/25/15 | Washington Nationals signed RHP Calvin Copping. |
| 06/25/15 | Washington Nationals signed OF Andrew Stevenson. |
| 06/25/15 | Washington Nationals signed RHP Kevin Mooney. |
| 06/25/15 | Washington Nationals signed RHP Koda Glover. |
| 06/25/15 | Washington Nationals signed Taylor Hearn. |
| 06/25/15 | Washington Nationals signed LHP Taylor Guilbeau. |
| 06/23/15 | Washington Nationals optioned RHP Joe Ross to Syracuse Chiefs. |
| 06/23/15 | Washington Nationals activated RHP Stephen Strasburg from the 15-day disabled list. |
| 06/22/15 | Washington Nationals signed RHP Russell Harmening. |
| 06/21/15 | Washington Nationals optioned RHP Taylor Hill to Syracuse Chiefs. |
| 06/21/15 | Washington Nationals signed RHP Mick Van Vossen. |
| 06/21/15 | Washington Nationals signed OF Angelo La Bruna. |
| 06/21/15 | Washington Nationals signed SS Clayton Brandt. |
| 06/21/15 | Tanner Roark roster status changed by Washington Nationals. |
| 06/21/15 | Washington Nationals signed RHP Matthew Crownover. |
| 06/21/15 | Washington Nationals signed LHP Grant Borne. |
| 06/21/15 | Washington Nationals signed RHP Mariano Rivera. |
| 06/21/15 | Washington Nationals signed RHP Jorge Pantoja. |
| 06/21/15 | Washington Nationals signed free agent 3B Chris Nelson to a minor league contract. |
| 06/21/15 | Washington Nationals signed RHP Adam Boghosian. |
| 06/21/15 | Washington Nationals signed OF Blake Perkins. |
| 06/21/15 | Washington Nationals signed RHP Ryan Brinley. |
| 06/21/15 | Washington Nationals signed RHP Tommy Peterson. |
| 06/19/15 | Washington Nationals placed RHP Tanner Roark on the paternity list. |
| 06/19/15 | Washington Nationals recalled Taylor Hill from Syracuse Chiefs. |
| 06/19/15 | Washington Nationals signed free agent RHP Erik VanMeetren to a minor league contract. |
| 06/18/15 | Washington Nationals activated RHP Doug Fister from the 15-day disabled list. |
| 06/18/15 | Washington Nationals optioned RHP Taylor Hill to Syracuse Chiefs. |
| 06/17/15 | Washington Nationals sent RHP Stephen Strasburg on a rehab assignment to Harrisburg Senators. |
| 06/15/15 | Washington Nationals signed 2B Ian Sagdal. |
| 06/15/15 | Washington Nationals signed SS David Kerian. |
| 06/15/15 | Washington Nationals signed 2B Dalton Dulin. |
| 06/15/15 | Washington Nationals signed LF Philip Diedrick. |
| 06/14/15 | San Diego Padres traded SS Trea Turner to Washington Nationals. |
| 06/12/15 | Washington Nationals placed RHP Aaron Barrett on the 15-day disabled list. Right bicep strain |
| 06/12/15 | Washington Nationals activated RHP David Carpenter. |
| 06/12/15 | Washington Nationals sent RHP Doug Fister on a rehab assignment to Harrisburg Senators. |
| 06/11/15 | Washington Nationals transferred LF Nate McLouth from the 15-day disabled list to the 60-day disabled list. Recovering from August 2014 right labrum surgery |
| 06/11/15 | New York Yankees traded RHP David Carpenter to Washington Nationals for 2B Tony Renda. |
| 06/11/15 | New York Yankees traded RHP David Carpenter to Washington Nationals for 2B Tony Renda. |
| 06/11/15 | Washington Nationals optioned LHP Sammy Solis to Harrisburg Senators. |
| 06/11/15 | Washington Nationals recalled Matt den Dekker from Syracuse Chiefs. |
| 06/11/15 | Washington Nationals placed 1B Ryan Zimmerman on the 15-day disabled list retroactive to June 10, 2015. left foot plantar fasciitis |
| 06/07/15 | Washington Nationals sent LHP Sammy Solis on a rehab assignment to Harrisburg Senators. |
| 06/07/15 | Washington Nationals sent RHP Doug Fister on a rehab assignment to Syracuse Chiefs. |
| 06/06/15 | Washington Nationals selected the contract of Joe Ross from Harrisburg Senators. |
| 06/06/15 | Washington Nationals optioned RHP A.J. Cole to Syracuse Chiefs. |
| 06/06/15 | Washington Nationals transferred RHP Craig Stammen from the 15-day disabled list to the 60-day disabled list. |
| 06/04/15 | Washington Nationals activated 2B Anthony Rendon from the 15-day disabled list. |
| 06/04/15 | Washington Nationals recalled A.J. Cole from Syracuse Chiefs. |
| 06/04/15 | Washington Nationals optioned SS Wilmer Difo to Harrisburg Senators. |
| 06/04/15 | Washington Nationals optioned RHP Taylor Jordan to Syracuse Chiefs. |
| 06/03/15 | Washington Nationals optioned CF Matt den Dekker to Syracuse Chiefs. |
| 06/02/15 | Washington Nationals recalled Matt den Dekker from Syracuse Chiefs. |
| 06/01/15 | Washington Nationals optioned LHP Matt Grace to Syracuse Chiefs. |
| 06/01/15 | Los Angeles Dodgers traded RHP P.J. Walters to Washington Nationals for cash. |
| 06/01/15 | Washington Nationals recalled LHP Felipe Rivero from Syracuse Chiefs. |