2009: Gee, Genie and rising popularity

On December 26, 2008, posters of the Girls' Generation members wearing roller-skates were posted up in various locations around Seoul. SM Entertainment's phone lines were blocked up by callers asking whether the posters were for sale and the company asked fans to stop taking the posters down for personal use. On December 29, the group's management stated that the posters were indeed teaser posters and that the group would soon release their first EP, Gee, in January 2009

A teaser video was released in January 2009 and the first single "Gee" released soon after. "Gee" topped Cyworld's hourly music chart on the release day.^[17] The song also went number one on all major digital music charts within two days The music video set a record on release, garnering one million views on GomTV in under a day.

The group began its album promotion in January 2009 on MBC Music Core where they sang their new lead single "Gee" and the track "Himnae (Way To Go)", another song from their mini-album "Gee" went on to become a phenomenal hit, breaking the record for consecutive number one wins on Music Bank with nine consecutive wins, as well as receiving a triple crown on SBS Inkigayo. The track also showed strength on other charts, topping the Mujikon, Melon and Mnet charts for eight consecutive weeks, the Dosirakchart for seven weeks, the Muse chart for six weeks, and the Baksu chart for four weeks.

After a short break, SM Entertainment announced that the group would be back with a new mini-album sporting a "Marine Girl" concept. The new single was to be titled "Tell Me Your Wish (Genie)", with the full mini-album being released digitally on June 22, 2009.The group started their promotional activities on June 26, 2009, appearing on KBS Music Bank^] The performance was followed by follow-up comeback performances on MBC Music Core and SBS Inkigayo on June 27 and 28, 2009. The physical release of Genie was delayed by SM Entertainment in order to redo the album art, and was released four days later on June 29, 2009.

The track proved to be a success as it conquered various music sites, including Melon, Dosirak, Mnet, and Bugs, and it was number one on the weekly charts and the SKT ringtone weekly charts of the first week of July. The mini-album sold an estimated 50,000+ copies in its first week after released (almost double the numbers from the first-week sales of Gee), an unusual feat for any Korean girl group.