Brittany Carter, 23, is accused of performing a sex act on the 29-year-old driver while Corey Jackson, 20, allegedly held a knife to his throat.
Police said the pair then stole $32 (Â£26) from the victim before fleeing the scene in the city of Findlay.
"We don't know why she did it," police Lt Robert Ring said.
"Maybe it was a distraction because they took money from him."
The assault unfolded after Ms Carter called the Trinity Express Cab Service in the early hours of 28 January, according to police.
She was arrested after the driver reported the incident.
Ms Carter faces first-degree felony rape and aggravated robbery charges in Hancock County.
She was indicted twice on drug charges in 2016 and is accused of heroin possession.
Mr Jackson remains at large and a warrant has been issued for his arrest, say police.
He is charged with aggravated robbery and complicity to commit rape, both first-degree felonies.

However, the government has insisted there is a link between the attack and Syrian Kurdish fighters.
Prosecutors and security officials said DNA tests had identified the bomber as Abdulbaki Somer, born in the eastern Turkish city of Van.
Last week's bombing killed 29 people, at least 20 of them military personnel.
"The bomber's DNA matches that of Abdulbaki's father," a senior Turkish security official told Reuters news agency.
Turkey's state-run Anadolu news agency quoted prosecutors confirming the report.
It said that Abdulbaki Somer was believed to have joined the Kurdish militant PKK group in 2005 at the age of 16 and was based in the Qandil mountains in northern Iraq until 2014.
The agency said that Somer's father had told police that his son was behind the attack.
Following the blast in Ankara, Turkish Prime Minister Ahmet Davutoglu named the bomber as Salih Necar, a Syrian national and member of the Syrian Kurdish People's Protection Units (YPG).
"Whatever the judicial inquiry concludes over the identity of the bomber, it is clear that the bomber came from Rojava, the area of the PYD," Deputy Prime Minister Numan Kurtulmus told reporters on Tuesday, referring to another Syrian Kurd-controlled northern Syria.
He said the bomber had entered Turkey from the region in the summer of 2014.
Turkish newspaper the Hurriyet suggested that Abdulbaki Somer may have re-entered Turkey with false papers under the name Salih Necar.
The PKK, which has been fighting for Kurdish self-determination since 1984, is considered a terrorist organisation by Turkey and its Western allies.
Turkey has also designated the YPG a terrorist group, but its allies, including the United States, back the YPG in its fight against so-called Islamic State (IS).

The former Tottenham player, 29, is the Spanish club's first signing since Neymar left to join Paris St-Germain in a world record transfer.
Meanwhile, Barca's Uruguayan forward Luis Suarez will be out for "four to five weeks" after he was injured in the Super Cup defeat by Real Madrid.
He will also miss World Cup qualifiers against Argentina and Paraguay.
Paulinho joined Tottenham for £17m from Corinthians in 2013, before moving to China in 2015.
He helped Evergrande win last season's Chinese Super League and leaves the team top of the table in the current campaign.
Paulinho said: "You have to face challenges with courage. I will try to do my job and I am prepared. It's a very satisfying moment. The dream I have been looking for has come true. I will give everything."
Barcelona are also keen on Liverpool midfielder Philippe Coutinho and Borussia Dortmund forward Ousmane Dembele.

The incident happened at Unst harbour about 06:50. There were no passengers on board, only four crew members and no-one was injured.
There was no loss of fuel from the vessel.
The ferry is currently alongside in Unst with the fire brigade pumping out water which was taken on board during the accident.
An Ohio woman has been charged with raping a cab driver at knifepoint before she and another man robbed him, according to police.
[NEXT_CONCEPT]
The bomber behind a deadly blast in the Turkish capital Ankara was Turkish-born, security officials say, not from Syria as the government initially said.
[NEXT_CONCEPT]
Barcelona have signed Brazil midfielder Paulinho from Chinese club Guangzhou Evergrande for 40m euro (£36.4m).
[NEXT_CONCEPT]
Shetland Coastguard was called out after the inter-island ferry hit rocks on its way from Yell to Unst.