In 1995, he founded InterAgro, a Romanian-Chinese joint venture.
Since 1996 Niculae has been the owner of the Astra Giurgiu football team.
In 1997, Niculae became the majority stakeholder of the Astra Ploiesti refinery, after a $16 million investment.
In 1998, he bought into the Romanian insurance company Asirom, after investing $21 million. He sold those stocks in 2007, making a profit of $65 million.
Since 2004, the total amount of agricultural Investments done by his company has surpassed €100 million.
Through his company, Niculae manages approximately 50,000 hectares of agricultural fields and is the biggest Romanian cereal cultivator. He is also the owner of 170 hectares of vineyards, reaping their first harvest in 2008.
In 2012, The Romanian National Tax Administration accused Niculae of defrauding the national budget due to accusations that his tobacco company, Galaxy Tobacco, had failed to pay its taxes, amounting to an excess of €120 million. Niculae fought the charges in Court and won.
In 2013, Niculae filed divorce from his wife, Domnita Niculae, ending a 31-year-old marriage. The divorce trial is still pending.
On 2 April 2015 he was jailed for two-and-a-half years for illegal financing the PSD electoral campaign from 2009.