My O-1 visa is about to expire and is in the process of being renewed. In the meantime, can I come back to the US with a simple ESTA ?

The ESTA allows approved individuals to board a carrier for the purpose of entering the US without visas for 90 days for visiting purposes under the visa waiver program. It is not intended to be a bridge until your O-1 visa is renewed. There is no authorization for work in the US under the visa waiver program. The fact that you have been in the US for so long under a working visa status may also be of concern to a CBP inspector at the port of entry even if you are approved for ESTA. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.

Hi. If you enter under ESTA, you will need to leave again to get into O1 status. Thus, when it gets approved, you will need to take the approval to the Embassy, get the visa and re-enter with the new O1.