Eintracht Frankfurt won the Europa League final after holding their nerve to beat Rangers 5-4 in a clinical penalty shootout as they claimed their first European trophy in 42 years.
The 46-year-old, whose appointment is subject to a work permit, arrives with Rangers sitting four points clear at the top of the Scottish Premiership.
Sparta Prague have hit out at media reports that Rangers midfielder Glen Kamara was targeted by sections of a crowd comprising mainly schoolchildren.
Gerrard has called on UEFA to take action after midfielder Glen Kamara complained of being racially abused by a Slavia Prague player.
Rangers have signed Switzerland striker Cedric Itten from St Gallen on a four-year deal, the Scottish club said on Tuesday.
James Forrest scored a late winner as Celtic won 2-1 at home against Rangers, who had Alfredo Morelos sent off for the fifth time this season, in a pulsating Old Firm derby in the Scottish Premiership on Sunday.
The Scottish club announced on Monday Dembele signed a deal to stay at Celtic Park until at least 2021.
Liverpool midfielder Ovie Ejaria signed a new long-term deal with the Merseyside club on Thursday before immediately being sent to Scottish side Rangers on a season-long loan.
Scottish club Rangers named former Liverpool and England midfielder Steven Gerrard as their manager on a four-year deal on Friday.
Dembele, 21, was born in France to a Malian family and started his journey with football at Paris Saint Germain academy.