The court said on Wednesday that the defendants were found guilty of "conspiring to carry out terrorist acts and of illegal possession of automatic weapons", in two plots foiled last year.
In one case, the court found four suspects guilty of conspiring to kill Americans who worked at an Iraqi police training centre east of the capital, Amman.
In the second, the court convicted six suspects, including two fugitives in absentia, of plotting attacks against Americans using five-star hotels and against shops selling alcohol and nightclubs in the capital.
Defence lawyers in both cases said they planned to appeal.
In the first trial, the court sentenced four Jordanians, who were arrested a year ago, to jail terms ranging between 10 and 20 years with hard labour. The four had pleaded innocent at the start of their trial nine months ago.
Military judges said the prosecution's allegations were "substantiated with strong evidence, and the court is convinced beyond doubt that the four were involved in a terror conspiracy on Jordanian soil".
The court initially sentenced three of the four defendants to death by hanging but commuted their sentences to 20 years with hard labour, saying it wanted to give the men a chance to repent.
The fourth defendant, Ibadah al-Hiyari, 24, received the lesser sentence of 10 years in jail with hard labour because it was not proven that he possessed any weapons.
The prosecution said that Maath Breizat, 19, al-Hiyari and the other two men monitored a desert road to the US-run training facility.
In the second case, the court sentenced the six, mainly young Palestinians aged between 23 and 26, to jail terms ranging between 10 and 15 years with hard labour.
Special forces police guard the
state security court in Amman
The group's plot was stopped when four members were arrested nearly a year ago in Jordan, according to their indictment.
It said the two fugitives, also Palestinian youths, are believed to be in Lebanon.
The fugitives were handed down the harsher penalty of 15 years in jail with hard labour.
The indictment said suspect Loai Hashem al-Sharif, from the West Bank, was elected leader of the previously unknown Khattab Brigades group.
Al-Sharif was responsible for recruiting fighters and raising funds to buy machine guns that were to be used in the attacks.