The board's decision clears Gunathilaka to play in the three-match series starting October 26 in the United Arab Emirates, though the final squad of 15 will not be announced until Friday.
The final will be played on October 29 in Lahore, where the Sri Lankan team bus came under attack from militants in 2009.
No top international cricket side has returned to Pakistan since then.
"The Executive Committee of Sri Lanka Cricket decided to revise the suspension imposed on Gunathilaka upon consideration of the appeal," Sri Lanka Cricket said in a statement.
Gunathilaka was suspended for unspecified "misconduct" during Sri Lanka's humiliating home series thrashing by India in which the islanders lost 9-0.
His fine -- 20 percent of his annual match fees -- remains unchanged.
Gunathilaka was dropped from the squad for the ongoing five-match one-day international series against Pakistan in the United Arab Emirates (UAE).
His reprieve comes as players express private concerns about the board's decision to play the Twenty20 series final in Lahore.
A source close to the board said skipper Upul Tharanga and Lasith Malinga were likely to pull out of the entire series due to security concerns about the final.
The board announced Monday that it would go ahead with the tour and "confirmed its commitment to play the third T20" in Lahore after assessments by government agencies, independent security experts and the International Cricket Council.
Sri Lanka Cricket chief Thilanga Sumathipala would accompany the team, the board added. In August he called for an end to Pakistan's isolation from world cricket.
Pakistan shifted their "home" matches to the UAE after the 2009 militant attack.
Since then, only low-ranked Zimbabwe has toured Pakistan, playing five limited-overs games in Lahore in 2015.
But a World XI squad comprising 13 players from seven top cricket-playing nations played in Lahore last month, with Pakistan hoping the visit would help end years of international isolation.
First Published: October 17, 2017, 5:47 PM IST