On both nights The Weakest Link has been the most-watched show among adults aged 18-49 across any network.
Almost 15 million households tuned in to the debut show to see Anne Robinson humiliate failing contestants, in a five-year record for US network NBC, beating rivals CBS and Fox TV in its timeslot.
Although viewer numbers fell to 13.7m on the second night, this represented a greater share of the TV audience and it was the top-rated show in some categories.
The figures confounded critics who had given it a lukewarm reception.
On both nights The Weakest Link has been the most-watched show among adults aged 18-49 across any network.
Tuesday's show attracted more viewers than any other programme shown at the same time, beating second-place ABC by 13%.
But viewing figures for the third consecutive show on Wednesday - as yet to be disclosed - could give a clearer indication as to the show's potential for long-term success.
After this launch week, the programme will only be screened once a week on Monday nights.
American TV critics have largely praised the The Weakest Link's format but panned Robinson's style.
Survivor
Robinson, however, has appeared unworried by their remarks, hitting back with her own caustic off-set comments.
She has also said she fully expects the show to be as successful in the long run in America as in the UK.
Meanwhile NBC has denied reports that Robinson is under armed guard because of fears for her safety.
British newspaper The Sun reported that NBC was worried that Robinson's rude comments to contestants could lead someone to attack her.
NBC has already announced plans for a special "Survivor" edition of The Weakest Link.
Robinson will preside over a panel made up of the former stars of the first series of rival TV station CBS's hit reality TV show Survivor.
The former Survivor contestants, including winner Richard Hatch, Susan Hawk and Sean Kenniff - will be seen battling it out on The Weakest Link on NBC on 10 May.
But NBC is prohibited by a clause in the former desert island team mates' contracts from even mentioning the show Survivor.
The Weakest Link is comparable to Survivor since it involves poorly performing contestants being voted off.
Hatch auditioned to be host of The Weakest Link before NBC hired Robinson.