The Diamondbacks activated Nelson (elbow) from the 60-day injured list Wednesday, John Gambadoro of Arizona Sports 98.7 FM reports.
Nelson was sidelined for the past three months with a right elbow strain, but he's finally been cleared to return after yielding two runs with a 4:0 K:BB over 2.2 innings in two rehab outings with Triple-A Reno. The 28-year-old will be utilized in a relief role down the stretch for the Diamondbacks.