Butler expressed his happiness with the deal on Twitter.
Feeling blessed! Y'all heard it here first! Deal is done!! SD I aint going no where!! Too excited!!
- Donald Butler (@DAButler56) February 28, 2014
At 25, Butler is one of San Diego's core players on defense. However, he has had trouble staying healthy, missing 24 of a possible 64 games in his four-year career. He missed three games last season with a groin issue yet was second on the team in tackles with 84.
The University of Washington product was selected in the third round of the 2010 draft, and he missed his entire rookie season because of an Achilles tendon tear in training camp.