The automated system, which officially launched in the US yesterday (February 16), will allow advertisers to manage their marketing campaigns and budgets without having to deal with sales representatives.
Advertisers will be able to specify how much they spend, pick cities or regions they want their ads to appear and write their own promotions. Twitter will only charge for those ads that are clicked, replied to or retweeted to other followers.
American Express will offer $100 (£62) to businesses who sign up the service on a first-come, first serve basis, which they can spend on promoted tweets and promoted accounts.
The platform will go live for the first 10,000 businesses who use American Express cards in March and will then be expanded worldwide to allow any company to use it later in the year.
The decision to court smaller businesses follows a report from the Chartered Institute of Marketing earlier this week that revealed nearly a quarter of the 900 UK marketers polled said that their activity on Twitter was not at all effective last year.