The Raiders promoted Cotton to the 53-man roster Saturday.
With Richie Incognito (ankle) ruled out for Sunday's game against the Chargers, Cotton will be brought up for reserve. Denzelle Good is expected to start in Incognito's place, however.
Cotton was waived by the Raiders on Monday.
Cotton was elevated from the Raiders' practice squad Saturday but did not see the field in Sunday's win over the Bears. The 23-year-old may return to Oakland's practice squad if he goes unclaimed on waivers.
Cotton signed with the Raiders on Saturday.
With Jordan Devey (pectoral) out for the season, Cotton adds depth as an interior lineman.