The Oakland Athletics traded for Neshek on August 3, 2012, for cash considerations, and immediately called him up from Triple-A Norfolk.

On September 22, Neshek gave up the game-tying home run in the bottom of the 13th inning to New York Yankees slugger Raúl Ibañez.
 The A's had scored four runs in the top of the inning, leading to a galling 10–9 loss the next inning.
 However, the A's defeated the Yankees the next day and went 9–2 to end the season, edging the Texas Rangers out of the American League West championship by one game, including sweeping the final three-game series in Oakland.
 In 24 games with the A's, Neshek tallied ​19 ²⁄₃ IP, yielding 10 hits and six walks, with 16 SO and a 1.37 ERA.
 He relied heavily on the slider, throwing it 83.5 percent of all pitches.

On November 30, 2012, Neshek avoided arbitration by agreeing to a one-year deal with the A's.
 He started the season well, posted a 2.34 ERA in his first 38 appearances into August, with 30 of them being scoreless.
 However, he gave up three runs apiece in two different appearances.
 Neshek attributed his early success to throwing almost exclusively sliders to right-handed hitters.
 Of all his pitches, he threw the slider 73 percent of the time in 2013.

The A's designated Neshek for assignment on August 26.
 For the season, he finished 2–1 with a 3.35 ERA and 29 strikeouts in ​40 ¹⁄₃ IP.
 He elected free agency November 5.
 Through the end of 2013, Neshek had faced 555 right-handed batters in his MLB career, holding them to a .181 batting average, .257 OBP, and .315 SLG.
 In 326 PA, opposite-handed hitters had more success with a .237 AVG, .328 OBP, and .432 SLG.
The Oakland Athletics traded for Neshek on August 3, 2012, for cash considerations, and immediately called him up from Triple-A Norfolk.
On September 22, Neshek gave up the game-tying home run in the bottom of the 13th inning to New York Yankees slugger Raúl Ibañez.  The A's had scored four runs in the top of the inning, leading to a galling 10–9 loss the next inning.  However, the A's defeated the Yankees the next day and went 9–2 to end the season, edging the Texas Rangers out of the American League West championship by one game, including sweeping the final three-game series in Oakland.  In 24 games with the A's, Neshek tallied ​19 ²⁄₃ IP, yielding 10 hits and six walks, with 16 SO and a 1.37 ERA.  He relied heavily on the slider, throwing it 83.5 percent of all pitches.
On November 30, 2012, Neshek avoided arbitration by agreeing to a one-year deal with the A's.  He started the season well, posted a 2.34 ERA in his first 38 appearances into August, with 30 of them being scoreless.  However, he gave up three runs apiece in two different appearances.  Neshek attributed his early success to throwing almost exclusively sliders to right-handed hitters.  Of all his pitches, he threw the slider 73 percent of the time in 2013.
The A's designated Neshek for assignment on August 26.  For the season, he finished 2–1 with a 3.35 ERA and 29 strikeouts in ​40 ¹⁄₃ IP.  He elected free agency November 5.  Through the end of 2013, Neshek had faced 555 right-handed batters in his MLB career, holding them to a .181 batting average, .257 OBP, and .315 SLG.  In 326 PA, opposite-handed hitters had more success with a .237 AVG, .328 OBP, and .432 SLG.
Pat Neshek